Do you have an original Commodore PET 2001 (‘chiclet’ keyboard model) with a broken-off key? If so, this is the part you need to fix it! When a key is broken off, the part that actually fails is the key plunger inside the keyboard, so this is the part you need to replace. The only tricky part of replacing it is removing the broken off piece of the old plunger from the keycap. I recommend doing this by drilling a tiny hole in the broken piece and then inserting a small screw in the hole to pull out the broken part.
This product is available for sale directly from Shapeways. Please order from the D’Asaro Designs Shapeways Store.