To make sure I did not have any extra proplems with sticking resin, I opted to entirely line the mold with parcel tape. It could well save a lot of agro, -the last thing you want to have to do is bash the mold around to get the beam out. That would be a sure fire way to upset the alignment.
Mold is about 3m long in total. I put it in the only available space I had, but it would have been a whole lot easier if I could have walked all the way around it more easily.