This is technically not necessary for mounting the FEP or NFEP to the vat. However, it does simplify things and assures that you get no wrinkles or lose corners. As you can see from the pictures, the idea is to put the FEP on the frame, using clips of some sort. Then it's just a matter of putting this over the vat, put the vat frame back on and tighten the screws. Of course, remember to tighten the screws in a crossing pattern as usual.
The author marked this model as their own original creation.