This is the mold I'll be using to mold my urethane wheels. The dowel pins will locate the halves when clamped together. I still need to add a couple screws tapped into half of the mold so I can separate it easily when it's done.
Ok, I think I've finished the mold. I've added the screws to separate the mold when it is done and made a dowel pin with a spring and pin retainer. This will hold the wheel hub in place in the mold so the urethane won't ooze under the wheel while it is setting up.
Here's a better shot of the spring and wheel hub in place in the mold.
This is the first wheel out of the mold. It turned out good, but the urethane doesn't stick too well to the aluminum so I'll probably use a light film of silicone around the aluminum on the next one so it will stick better. The wheels are 1.187" wide and 1.250" diameter.
Wheel assembly with the baseplate mounted.