LEGO-compatible low-poly floating boat hull

A generic, robust boat hull compatible with standard toy bricks. Low-poly design leaves plenty of room on the inside and more space for the imagination (Pirate ship? Space ship? Pirate space ship? It can be anything).

A grown-up audience may first see a dull cargo barge but a shallow bottom is simply the most practical for actual playing - interior space, stability on solid ground and it needs little water height to float. Bath tub compatible.

HMS Benchy:

The model comes with an optional deck that attaches via conventional studs.

The hull is a single piece:

All the available top surface is covered with studs...

... that are raised as needed:

The bottom surface is completely antistud-covered:

Antistuds on the edges are widened and reinforced (they are not intended to snap-fit but to provide clearance when a flat plate is attached that extends beyond the edge).

Studs and antistuds are tapered slightly for more robust snap-fit:

Printing:

Print only .step files (not .stl, "preview only") for better accuracy. A 0.4 mm nozzle is recommended. 0.6 mm can me made to work.

Recommended material: PETG (PLA would be easiest but creeps over weeks and months). Double-check that the material is really dry, otherwise cracks between layers will cause water to seep into infill. 

If in doubt, slow down the print (e.g. volumetric flow rate cap: 5mm³/s) for water-tight layer fusing. A "Quality" preset is clearly the better choice than "Draft" mode - time buys watertight layer adhesion. Printing overnight? Use the time.

Do not use support or brim, it is not required. Supports may be near-impossible to remove.

Check antistud bridges on the test print. If test bricks don't stack cleanly, slow down and / or increase fan on external bridges.

If using only 3 top layers, slow down internal bridges, or they may show through on the surface. Two top layers (typ. 0.2 mm x 2) are too thin for mechanical forces when attaching bricks to studs. Four top layers (~0.8 mm) is a common slicer default, sturdy but expensive.

I use 5% Gyroid infill and two wall loops. The walls are fairly stiff already: Only minimal infill is needed for strength, but internal bridges get quite long.

Tolerances:

The overabundance of 3d-printable "compatible bricks" hides the fact that printing functional ones is actually a real challenge: The required tolerances for snap-fit are extremely tight. To avoid wasting a long print, a 3x3 calibration plate is included. Print it first to confirm that studs and antistuds work as intended. If antistuds seem impossibly tight, check first layer settings, e.g. elefant foot compensation 0.1 mm (Prusa recommends 0.4 mm)

Expect snap fits that are somewhat tighter than toy store parts, especially when mating two printed parts. It's not necessarily a bad thing, once kids get used to it.

Studs, antistuds and body are separate objects in the .step file e.g. to print in multiple colors.

The whole design is generated by script - if you run into issues and really want to print it, ping me. A 350 mm "L" version is currently under development, test-printing.