Seriously, that would sell. Or a lightsaber. The Venn diagram of "3d printer owners" and "ST/SW fans" would be 2 circles drawn nearly on top of each other. Charge $15 for the d/l. You'd overheat a T1 line

how about custom sex toys?

And I thought I was having a wacky idea. Actually, I'd probably be too paranoid about medical issues to touch that. The story that will inevitably ensue when a group of 11 year old boys start printing whale penises and taking them to school to frighten the girls with would be hilarious though

...the problem is not PVC whale penises; the problem is how we can monetize these ideas we come up with:)

I would start off small. A warp core maybe out of reach for most.

How about a Flux Capacitor?
Oh look, the plans have already been made