Thanks for the response. I've tried 1 by wood as the core for my coils. I've also tried dowels. The quarter inch thick wood seems a better thickness. I might even try to plane that down to something like 3/16 of an inch.

I suspect my post was not clear. I'm talking about two different steps. First, using the plexiglass as a mold for the nine individual coils.

After molding and setting the coils in whatever glue/resin to hold them together, that plexi and wood would be removed and probably discarded. Pure copper would remain.

Then there would be one thickness of plexiglass to which my nine coils would be glued. This should leave me with a stator in the range of 3/8 to 7/16 inches thick.

A difficulty I always seem to have is that my fiberglass molded stators often vary in thickness. This often forces me to have a wider gap to accomodate the less than "plumb" and uniformly level surfaces. I just haven't found the right process to end up with a level molded surface. The plexiglass should be uniformly level, while adding minimally to the thickness.

The plexiglass I have is about an 1/8 of an inch thick.

Don't forget, it is important to use clamping-down method while epoxying the sandwich. This will keep the stator thiner and the clamps can be adjusted to get an even thickness ALL AROUND the stator disc as you can squeeze the coils down (Unless you already have the coils wound in high density, which is not so easy to do in homemade situations). That too, you won't even have to fabricate spaces. Using 4 or even 6 clamps around the disc can get must precise height adjustments than using the "Lazy" 3 clamps. With 3 clamps, sometimes you might think you got it under control but when the resin or epoxy is dried and you opened the clamps, you would find the uneven thickness still. (Sorry for the outburst "Lazy", did not mean to contradict others. Just wanted to update ideas. Get the drift ? :-)