I recently fabricated a couple of airplane parts (non-structural) using off the shelf resin, from Oreilly.
I had one broken part from which to pull a negative mold. using tape, cardboard, and bondo. I managed to "repair" the broken part well enough to get a mold.
I had some old bondo on the shelf, that had gotten old, and is useless for anything except making a mold. I cast my mold, and laid in the glass using my usual method.
I cut my fabric, or mat, to size, and lay it on waxed paper, then "pre-preg" it with mixed resin. Then flip it over into the mold, and using a bondo spreader, squeegee it into the mold, removing excess resin as I go. pull off the paper, and repeat, with as many layers as needed. Then let it set.
Out came a decent part, and I still have the mold to make more.
No sticky glass, mabe has to do with the waxed paper, mabe has to do with the release agent, I don't know.
pic1 ready to cast mold, 2 the mold, 3 in the mold, 4 ready to be trimmed, and painted.