I've found forums for playfields and for backglasses/translites, but nothing for ramps. This forum is for people looking to buy, sell or trade ramps. If you are looking to buy a ramp, post it here, but also post in the freeplay40-ramps forum as he manufactures ramps for a given title if enough people are interested. freeplay40 works closely with Larry at Starship Fantasy so that they aren't both working on the same title.
For reference here is a forum for playfields:
For reference here is a forum for backglasses/translites: