A MUCH better way of going about the subject than trapping the work.
I use shop-made shims all the time with edge forming bits that need them. The LV kit looks like a nice commercial solution.
Hobby shops that cater to model builders sell styrene sheets in .005+ thicknesses. "Evergreen" is one brand name. The thin stuff is easily cut with an Xacto knife or scissors, the thicker sheets can be coped or scroll sawn. Too lazy to cut it? Evergreen even makes precut strips! <G>
The "Odds & Ends" bag will probably have everything a woodworker might need.