You are best off getting your own printer. They are pricey but if you know CAD, there is nowhere else to go. These guys have proper 'resin' (Not filaments): http://formlabs.com/products/materials/flexible/ that you can use to make some kick ass parts.
If I were you, I wouln't waste time creating my own designs. Pinshape has some tight paintball stuff as well (Mostly free too). Like this tactical flashlight mount. Turns out pretty nice too.
Noticed the thread is kind of old but if you have an update on this, love to hear about it. 3d printing is dope but yeah still pricey. At least the materials are getting better so I would give this tech more time to get more out there.
Thanks for the offer! I have however sorted it by getting a job in 3D printing myself I work for 3T RPD, which is known to a few people on here. I can confirm that we will print paintball parts and the whole assemblies!