I was able to separate the first seat with 4 layers of fiberglass (plain old duct tape worked well and released well). 4 layers was not going to be thick enough, but I wanted to get the shorter seat form done as I could add layers later.
Here is the 1st pan for the small MX tank. I needed to do a better job forming the sides so the next layers will have to be better and I formed the tape on the frame for a better mold for the shorter pan with the XS tank.
Working with the fiberglass is tough in the shop. The fumes are bad so I can only do it after we close and I usually need to get back to the family. Things were slow at home last night so I headed back to the shop to get the forms done.
The form was already modified for the stock XS tank so I just had to precut the fiberglass sheeting and stage the resin. Here is the shorter form for the stock tank and the 1st pan on the bench waiting for additional layers.
After 10 sheets of fiberglass:
And an additional 4 sheets on the 1st pan:
Everything was dry this morning and I was able to separate the second seat pan (although with 10 sheets it took some work). Both pans are plenty strong now. Tomorrow I'll get the excess cut off and shape the final pans. Then it will be adding the rubber mounts to sit on the frame and making the front and rear brackets to attach each seat.