Spacetime Globe

The model should be printed at 1.8 scale for every piece for best results. REQUIRES ADDITIONAL PARTS: 12 4mm diameter 250mm length steel (or other stiff material) rods. rods. Colored 1/8 inch push pins to use as event markers.

ASSEMBLY AND PRINT INSTRUCTIONS

Quantity of each piece per model: Baseplate, 1; Gridlines, 1; Cubes without Nubs, 20 (I recommend an extra or two; Cubes with Nubs, 16 (same advice applies); Endcaps, 24.

To assemble, take the baseplate and place the cubes with nubs in the troughs in the pattern described: place 1 cube in the first trough along the diagonal axis of the baseplate, in the next trough place two cubes, alternate with one cube then two cubes until you have used all 16, both the first and last trough should have only one cube. This makes the "spine" of the model. With the remaining cubes without nubs, place them so that a 6 x 6 grid forms. Since they don't have nubs, they are not fixed to anything. Ensure all the holes in the cubes align with the corresponding slits in the baseplate walls. If they are not, simply rotate them so they are. Next, carefully push the rods through the outside walls and through a row of cubes. Once all 12 rods are used, each cube should be constrained by two rods, one per axis.

Next, using adhesive, add the endcaps onto each end of the rods, make sure they are on as deep as possible to limit the twisting of the rods.

For use, place push pins in linear patterns to denote multiple moving objects with different speed, use the grid to line up pin locations. Using the endcaps to shift the model is how you shift between said perspectives accounting for special relativity. Reference MinutePhysics for inspiration on how to best use models to teach relativity.