As to laying the materials onto wax paper. It might work OK for very small areas but you will end up with wax contamination on the surface and that will interfere with bonding. The heat generated by the epoxy might be enough to melt the wax and that would be difficult to remove. It could interfere with a later application of more epoxy or an application of paint. So don't do it there are easier ways to do the same thing and they don't contaminate the surface.
There is a product sometimes called peel ply that is a type of fabric. Just go to youtube and enter peel ply tutorial into the search box to see how various people do it. Bust basically you build the layers up on top of it then take it over to your panel and leaving the peel ply in place roll it down onto the surface. The peel ply helps your applicator glide over the surface. The peel ply remains on until the epoxy is cured at which time it can be easily peeled off, hence the name peel ply.
For small patches you can use plastic sheeting from the hardware store, I have personally done that method for applying patches quit a few times. Just tape it down at the edges onto a flat surface. Spread out your fiberglass cloth,roll and/or brush the resin onto the cloth building up as many layers as you need. If creating a patch all the layers should not all be cut to the same size, you want to create a graduated thickness at the edge. The first layer against the plastic is the smallest, then each subsequent layer is slightly larger than the previous one. The last layer is the one that will be against the surface you are applying it to. Don't put too much resin on, just enough so that the glass turns transparent instead of white. You can build up a stack of layers. Then take it to the project, put the patch in place and very carefully remove the plastic. You must take the plastic off before the resin cures. If the layers lift up a bit when you take the plastic off just smooth them back down with a squeege, brush, roller, etc.
