Pewter Casting Soccer Ball

In the fall of 2023 I took ME10 at Tufts with Professors Luisa Chiesa and Gary Leisk. For our final project, Jean Pascal Cyusa, Paul Galvan, and I decided to cast our own version of the Ballon d'Or — the trophy given out every year to the best soccer player in the world, won in the past by players like Messi and Ronaldo — out of pewter.

Starting Small:

None of us had cast anything like this before, so we started small: first casting simple spherical objects like a hacky sack and a stress ball just to get a feel for the process.

From there we moved on to casting a hollow shape, since the final ball needed to be hollow to keep its weight and pewter usage down. We 3D-printed a mold, dusted it with a release powder, and pressed a sacrificial core into shape before pouring — and it actually worked, coming out as a clean hollow scoop.

3D-printed mold dusted with release powder for the hollow casting test

Sacrificial core for the hollow casting test

Casting the Ball:

Casting the actual ball turned out to be a much bigger challenge than any of our practice rounds. Our original plan was to sand cast two halves of the ball separately, then assemble them onto a stand. One of my teammates suggested we try lost-wax casting instead, using a wax mold pulled from a vacuum-formed mold, so we ended up compromising and casting one half with sand casting and the other half with lost-wax casting.

Both methods turned out to be far harder than we expected, and creating a hollow core inside the ball was the real sticking point in both — we couldn't get either one to core out cleanly. In the end, neither sand casting nor lost-wax casting was what actually worked. What did work was using an actual half of a real soccer ball as a mold to make a plaster mold and core, then pouring molten pewter directly into that.

Plaster mold made from a real soccer ball half

Plaster core for the soccer ball casting

Finishing Touches:

Once the half-ball casting worked, we bolted the piece together with more pewter, mounted it on a plywood base, and used a CNC router to engrave our names and "ME10 Final Project" into the wood. We couldn't have gotten through all those failed casting attempts without a lot of help from the staff at the Bray Machine Shop.

The full final project writeup is below:

Open the full ME10 final project writeup