TETRIS – Modular Tetromino

Backstory:

I grew up in the ’90s — countless hours spent playing TETRIS, and that iconic theme song is still stuck in my head!

In July 2024, I printed a very simple version of this legendary game — a basic, charm-less design where magnets were manually inserted during a print pause (M601).

By October 2025, I wanted something smarter and modular — a customizable Tetris set to decorate my TV console (IKEA FJÄLLBO).

The idea:

Create TETRIS pieces (tetrominoes) that can magnetically attach to metal surfaces while remaining fully reconfigurable.

How it Works:

Each tetromino is made of four modular cubes, each cube being a 25 mm square (12.5mm high) built from two printed parts:

• TOP the colorful visible surface.   
• BASE the structural layer featuring a print-in-place bearing system with a central slot for a 6 × 6 mm cylindrical magnet.

Note: The base and bearing print as one single piece — no post-assembly needed. Once printed, the bearing can rotate freely after being loosened with the provided tool.

To create the seven Tetris shapes (I, O, T, J, L, S, Z), choose between three connector types:

• Double-side clip connector detachable on both sides; perfect for full modularity.
• Half-fixed connector detachable on one side only; the other side is locked once the base is screwed to the top. Great for kid-safe builds or to prevent small parts from being lost.
• Fixed connector non-removable, both sides are locked once the bases are screwed to the tops.

Note: I printed the three connector types in white, grey, and black for easy visual distinction.

Two small TOOLS are included:

• Bearing release tool to free the bearing if it’s too tight after printing (see GIF).
• Screw & magnet tool to screw the base under the top and/or extract a magnet if inserted the wrong way.

Additional Materials:

• Magnets Ø 6×6 mm (cylindrical)

Technical Specifications:

• Printer used: Prusa Mini+
• Nozzle: 0.4 mm (extrusion width: 0.45 mm)
• Filaments used:
  • Polymaker Polyterra PLA: for the colorful tops (nice matte finish)
  • Polymaker Poylite PETG: for the bases, connectors and tools

Printing Instructions:

TOP (color – PLA)

• Layer height: 0.15 mm (first: 0.2 mm)
• 2 perimeters | 5 bottom layers (0.8 mm) | 4 top layers (0.6mm)
• Bottom fill pattern: Concentric
• Infill: 15% Gyroid

BASE, CONNECTORS and TOOLS (PETG)

• Layer height: 0.15 mm (first: 0.2 mm)
• 2 perimeters | 5 bottom layers (0.8 mm) | 4 top layers (0.6 mm)
• Bottom fill pattern: Monotonic
• Infill: 15% Gyroid

Special transparent TOP – PETG (just for fun)

• Layer height: 0.1 mm (first: 0.1 mm)
• 2 perimeters | no bottom/top layers
• Infill: 100% concentric

Assembly Instructions:

1. Use the Bearing release tool if needed, loosen and activate the bearing’s motion (see  gif).
2. Insert a 6 × 6 mm cylindrical magnet into the central slot of each base (check polarity — all magnets should face the same way).
3. Choose and position your connectors (half-fixed or fixed) between cubes before screwing them, depending on your preferred configuration. (Refer to the note and the illustration for how I use them.)
4. Screw the BASE under the TOP using the Printed Screw & magnet tool. Make a quarter turn clockwise until it locks in place.
5. Combine your cubes into any Tetris shape you like and attach them magnetically to your favorite metal surface!

Note: From step 2 to step 5, you can follow the assembly video for a clear step-by-step demonstration.

In my setup, I use one of each connector type per Tetromino.

Every tetromino includes two cubes positioned side by side — for that connection, the fixed connector is recommended to ensure rigidity.

For the two other cubes, I suggest using half-fixed connector, since at least one side of the connector will always remain in contact with another cube.

Exception:  If you want to combine four different color cubes or intentionally break a shape to create a more open layout or visual “split” effect, you’ll have one exposed connector side.
In that case, use the double-side clip connector to keep everything consistent and secure.