I see where your going now
UV resin?
It may be a good idea to go with a short focal length, having a beam that has a big DOF may affect the layering, (I'm guessing you will be using a bath of resin and not laydown?)
Lemme have a dig through my trade catalogues in the morning for good lens suppliers, most of my stuff is IR but the work I've done in the UV spectrum used lens's from Edmund Optics
(
Edmund )
Very good but expensive in long focal lengths

Have a look at their plano convex defense lens's, reasonable price (40 bucks),
RMI are also very good but limited on the wavelengths they cover
RMI
May also be worth looking at dental suppliers, they use a UV cured resin in tooth repairs (I have a feeling it's diode (LED) based though and not laser as such)
I'll be very interested in how you get on though, 3D printers are great fun but the material science isn't quite there yet (I have a Z-corp 650) not to mention so dam slow
One of my clients builds 3D printers (Rostock based under licence) and every month I get the joy of cutting out all the sub assemblies
best wishes
Dave