Create 3D Building Blocks Using Tinkercad

I don't have a 3D printer or filament — what can I use instead for this project?

If you don't have a 3D printer, export each grouped part as an STL (step 'Export each grouped part') and either upload those STL files to an online print service or substitute by tracing the 30×30×30 mm cube and 60×30×15 mm rectangular block onto foamboard or cardboard and cutting/gluing layered pieces to match the shapes.

The peg doesn't fit into the socket after printing — how do I fix the fit in Tinkercad?

If the 5 mm peg is too tight or loose in the 5.3 mm hole, adjust the hole diameter in the Inspector by small increments (for example try 5.5 mm for a looser fit or reduce the peg to 4.8 mm), and make sure the hole actually intersects the rectangular block slightly before selecting Group so it cuts the socket.

How can I adapt this activity for younger children or make it more challenging for older kids?

For younger children, simplify and make parts larger and safer by increasing the cube to 50×50×50 mm and the peg to about 8 mm diameter by 4 mm height with an 8.5 mm hole and pre-print the pieces for assembly, while older kids can keep the 30 mm cube and 5 mm peg and experiment with snap-fit tolerances, more complex connector shapes, or adding magnet sockets after exporting the STLs.

What are some ways to extend or personalize the blocks after following the basic instructions?

Personalize by adding Text or patterned Hole shapes to faces in Tinkercad before Grouping to emboss names or textures, choose colorful filaments or multicolor printing in your printer software after exporting the STL, or drill and glue small magnets into printed sockets to create stronger, reconfigurable modules and then photograph your finished set for DIY.org.