The 10366 Tropical Aquarium will be released in mid November. In our previous article, we looked at the overall build experience. The set is the most expensive LEGO® Set that is not based on an external IP, such as a movie, or large piece of architecture. The final model is also quite large. I suspect this will be a model that has its ardent fans, but a lot of people will, quite rightly, be put off simply by the $AUD699.99/USD379.99/ €449.99 / £399.99 price tag.

Despite the pricing, this set is not without its merits. Today, I want to show you some of my favorite learnings from the set, which can be translated into models of your own. If you think they are interesting things, download the manual, or look up the relevant parts of construction in the LEGO BUILDER App. In my next installment, I’ll look at some other ideas for customising the model, while I intend examine the value in fourth of my review series. I am grateful that the LEGO Group sent a copy of this set over for review: all opinions and thoughts in here are my own.

Things are more sturdy with a robust base

This is a big set, and ultimately quite heavy. A strong base is essential to be able to transport the model, without worry, around the house. Indeed, there is something to be said for a sturdy base, if you are building a diorama, if only so it doesn’t collapse under its own weight as you slide it into position 10 minutes before the expo is due to open its doors.

We build up a collection of crosses, strenthened by the use of wedge bricks at the centres, with double layers of plates at the points of brick plates While these modules felt somewhat flimsy as I put them together. As we built it up, we added some grey crossbraces to strengthen the form.

Once the frame is built up, it is covered with 16×16 plates on top. there is some texturing added across the base with curved tiles, as well as round slope bricks, and the ‘curved wedge slopes. Some regions are tiled, and there are a few turntable bases placed around the board, in pairs. We will come to these shortly. We add a bit of landscape onto each plate as we go, filling the base up with eight of the 16×16 plates. By the time the plates are filled in, the base is extremely robust – six plates thick all up.

Details are added to the surface in the form of sand mounds and snail trails, while dark tan tiles will make it easier for subbuilds to be attached, independent of the grid. Which leads me to…

The Power of Pythagoras

Fifteen year old me just screamed, and not in a good way. As much as I enjoyed middle school maths, something about Pythagoras’s theorem always ticked me off. I suspect it was my occasional failure to take the final square root when calculating the hypotenuse.

Here’s a quick reminder:

For any right angle triangle, the sum of the squares of the two sides is equal to the square of the hypotenuse:

a² + b² = h²

Due to the fractional nature of square roots, many of these triangles end up featuring dimensions that do not work out well in LEGO form. So we look to Pythogorean triples: triangles whose sides are all integer measurements. The simplest has sides of 3 and 4 units, producing a triangle with a hypotenuse of 5 units in length. [Other examples of these pythagorean triples include (5,12,13); (8,15,17);(7,24,25) and (20,21,29)]

3²+4² = 9+16

9+16 = 25

h²=25

h=5

Let’s consider one of these pairs of turntable bases as the hypotenuse: With the turntables placed at the lower edge, and then offset 3 studs to one side, we have a 3-4-5 triangle. As you can see, the hypotenuse is 5 modules long. Thiss allows the module with the turntables seperated by a plate to be attached to the base, aligned at around 53º/37º to the primary grid. (but wait, ramblingbrick – those are 4 stud and 5 studs long plates. I appreciate that. we take the distance fron the centrre of the first stud to the centre of the last.)

Tied in with this section is the important idea is that for movement or play features to be included in a model, planning for their mechanisms needs to start relatively early. Here we see at least three mechanisms brewing: one on the right, one in the centre and another on the left.

Moderately interesting SNOT Techniques:

Not too simple, but possibly not super advanced. We see two plates used to space the bricks with studs on the side, so that they are perfectly spaced to serve as the sonnection point for slopes running up the side of the rockwall. A brick is 3 plates high, while a standard LEGO Module is 2.5 plates wide. Take a look at this example, building up texture around a big ugly rock piece. We see a bracket wrapping up beside some (studs up ) elements. This brick+bracket structure works out to be 3 plates thick, aligning nicely with studs on the rock wall.

The spacing of the white SNOT Bricks allows a brick or plate to be attached smoothly, with the studs pointing out to the side. This is above the dark tan slope and tile, with a bracket wrapping up the side. The grey 1×4 slope clicks onto the white SNOT bricks: the top of that sloped brick lines up with the brackets, perfectly.

We double up with a near mirror image, and start to create a cave over the slider that will become the crab run.

Realising the Fantasies of scale.

Recurring patterns appear throughout nature. However, most LEGO sets will only give you a hint of a recurring pattern, or just include a few examples of an interesting element. This set brings a few examples of large collections of similar elements are placed in close proximity to each other, to brings us intriguing organic forms, on a scale dwarfing most of the Botanical Collection. In the normal context of MOC design, you might find yourself wondering about how a repeated effect might work, or a large cluster of similar stalks – such as in a jungle, cornflield or an underwater/alien landscape – and this set produces several variations on these.

The Orange anemone brings similar stalks into close apposition, and to add to the detail, it also brings a grid of 9 gears, all interconnected. This effect works well, but since the anemone’s tentacles are curved, they will collide before they are rotated very far. Fortunately, there is a slip mechanism built into the connections between the axles and the tentacles.

The other example is the purple anemone. Using a combination of lavender, and opalescent transparent purple, this is a more static display piece.

This starts off with a pare of trapezoids, filled with Technic pins. Some clips on the revers side of the trapezoid allows for the this panels to clip onto a couple of bars, on an angle. Next: we add the purple tails, and cap them off with a ‘lamp’ element. Ultimately, this quite parts intensive, with 38 tentacles slotted into the somewhat limited space.

In the final step, we mount the anemone inside a recoloured ‘Pixar Lampshade.’

We see a the use of further recurring patterns for some branching coral. While tucked away in the back corner of the model, we see an interesting use of round bricks and branching vine elements.

Variations on a Theme

The different types of coral featured in the set all share a common core in their construction – a recoloured 2×2 circluar plate with surrounding bar.

These elements are stacked with circular 2×2 plates and 2×2 tiles with a central stud to space them out, with different elelments used to produce the final corals, including chef’s hats, pith helmets, broom heads and mops. I appreciate the way that similar techniques are used to produce a collection of dramatically different corals.

These elements use different types of claw techniques to clip onto the ring, and some (particularly the pith helmets) use different elements to vary the distance between the clips and decoration, allowing for better spacing.

Here is a closer look at the pith helmet construction: you can see that the second ring here uses two plates, rather than a brick to hold the helmet onto the clip.

And, to prove my point, here are a couple of brand new coral hybrids…

As I showed in my main review, the different forms of coral are relatively simple to move from point to point around the tank.

There is no need to leave the modularity at this level:

On LEGO.com’s feature page for the set, designer Sven Franic presents some alternate approaches to customise the set for display, substituting whips, carrots, whips and pumpkins into the build. Chances are, if you are going to get these elements in industrial quantities, you might need to visit LEGO’s Pick a Brick site. Unfortunately, the circular ring is not (at the time of writing) available in tan on PAB – but you might choose to use the parabolic ring instead.

A Variation on the Variations

The water weed is probably one of my favorite features in the set – the use of the different coloured leves – dark green(earth green) and transparent green, as well as transparent clear and violet in another. The leaves connect directly onto the bars of windlass elements, and the use of connectors with a peg and axle allow these modules to twist along the weed – ensuring that the leaves are not fixed to the grid.

A new element, and how you might choose to use it

The set comes with a new element mould – lets call it a ‘fin’ in search of a better name. This element appears 30 times, in 5 different colours. In this debut appearance, it appears in cool (bright light) yellow, reddish orange, aqua, transparent clear and transparent green.

This fin is one module wide at the thick end and features a bar connection. It tapers at 90º to the bar, and forms a inwardly sloping, triangle.

The fin element 3 1/2 plates high at the thinned end. When this edge is vertical, the top corner is one plate above the bar connection, and the lower corner is a little over 2 plates below the bar. In this position, the fin extends 3 modules beyond the clip it is connected to.

The set demonstrates several different techniques to attach this fin to a model:

The not quite a clown fish uses the fin, attached to 1×2 plates with a clip on the long side, alternating with a plate. The fins fit fairly closely together, and can maintain this fit over a degree of rotation. The element can be stacked to adjust the size of the tail.

The Rainbow Fish uses a similar technique at the tail, and attaches the bar to an upright clip – and moves toowards the rear, over a 1×1 tile, to approximate the shape of the 1×2 bow. underneath, it is attached using a clip on a bar, and runs towards the inverse 1×4 curved bow.

The White ‘angel fish’

Again, this fish stacks 3 fin elements to make the tail. The dorsal fin virtually matches the curve over the 1×3 bow brick.

The purple and orange ‘Angel Fish’ has a slightly different shape at the rear, so the curve is dropped relative to the transparent clear fin. There are also 1×1 tiles with an upward clip, attached to the sides of the fish’ body, allowing the fin element to face sideways.

In conclusion

Today I have reflected on some of the aspects of the build that either left me intrigued, or strangely satisfied. The 10366 Tropical Aquarium has some interesting features which may be readily adapted for your own MOCs. It also gives us a new mould, the fin element.

The final model is extremely sturdy, thanks to multiple layers of elements in the frame of the base. There are recurrent uses of the 3-4-5 Pythagorean triple throughout the build, taking some structures off the grid. The walls of the cave, and orange anemone mechanism are built up with bricks both upright and on their side.

The set uses multiple variations on the ‘unexpected part clipped to a circular rail’ to give us the different forms of coral seen within the set. An alternative repetitive technique is used to build up the water weed.

Finally, we are introduced to a new fin element, which is used in multiple different ways, between the different fish in the model.

These are not the only interesting building techniques used in the set, and there is plenty of inspiration to be taken by looking through the instruction manual when it becomes available online, after the set’s release in the middle of November.

I hope you have enjoyed this journey through some of my favorite building techniques used in the 10366 Tropical Aquarium.

This set won’t be for everyone, in part due to its overall size, niche subject material and its overall price. I’ll look at the over all value in my 4th post (after I have done the sums).

However, next time, I will present some of the ways that I would consider using this set on display.

If you want to take a closer look at the overall buildling experience, as well as the selection of elements, check out part one of my review, and sign up to our mailing list to make sure you get reminded when the future installments are released.

How do you feel about this set? Please leave your comments below

The 10366 Tropical Aquarium has 4154 pieces and will retail for $AUD699.99/USD379.99/ €449.99 / £399.99. It is available for preorder now, and goes on sale in mid-November 2025.

If you have enjoyed this post, please feel free to share it with your friends, families and communities. You can also keep up to date with us by following The Rambling Brick on our socials: Facebook, Threads, Bluesky, Tumblr (or just sign up for our mailing list) and find some extra content on Instagram and TikTok.

We really value your feedback: please let us know what you think about the sets we review, and the articles we post. And if you wish to support the Rambling Brick, consider clicking on our affiliate links before going shopping at LEGO.com. The Rambling Brick receives a small commission, and it costs you nothing extra.

Until Next Time,

Play Well!