I just use cedar shingles; I've got bundles of them lying around. The slope is about 3/8" at the butt to zip at the tip.
I have a set of these, and you're correct, they are very handy. The photo shows them being used to check size/spacing of some small drawer fronts before assembly and attaching to the drawers.Some good tips here. I've been finding these shims very handy too: Polypropylene Shims - Lee Valley Tools They were selling smaller sets for $4 but I don't see that package anymore. I've been using them to set door heights on cupboards so I can accurately mark hinge locations. The thinnest ones are only 1/32" thick so you can do some fine tuning with them.
Tile setting wedges. Really inexpensive. These arn't the ones I have in stock but very similar...
https://www.amazon.ca/QEP-10285-Til...&qid=1518119742&sr=8-10&keywords=tiles+spacer Too bad it doesn't ship to U.S. :crying: