I agree with the wall thickness, can be thin as long as there is 100% epoxy behind it.
There will be a small space between the insert & blank.
What I have found is drilling the stuff is easy but you need to go up in reel seat size. This is because I am making the skeleton ends fit over the corian this section gets veeeery thin and the need for more precise equipment. Doing that makes the inside diameter smaller. eg; am making a Patriot Allstar 1088 and would normally use a 18 seat now I need a 20. Oh and if you ever do this its cheaper to cut your own skeleton out of the body than buy a premade skeleton.
Where did I get the Corian from....hmmmm - thanks to my bro.
I did do a little buff test -
* finish sand w240 = lite shine
* finish sand w320 + scratch remover wax stuff (white) = wicked shine like glass
As far as a seat to buff let me get my $h!7 together & ill get a couple to yah. Ive only made 3, they make a huge mess but look great.