Until yesterday, I did not have an acrylic stamp block to use, so I was using a piece of polycarbonate. The problem with it is that it is still slightly bendable, not the best thing to use. So, if you are looking at saving money on stamping, I suggest you buy the blocks in sizes you need and save the money on the stamps instead!
Having a Silver Bullet, I am fortunate to be able to cut most fun foam that I find. If you have a Cameo, you will be stuck with only the thinnest, sorry, but true.
The thin fun foam is ok for sentiments - as long as you are careful with it as it is fairly fragile but you are not going to be talking extra fine here. To make stamps where the letters are not joined, stick them onto a piece of acetate with permanent spray glue and use that to adhere to the block with temp adhesive. That leaf doesn't belong here, it's the thicker foam!
The thicker fun foam is great for the not so delicate stuff. Items that have thick lines or solid patches do well with this.
Just incase you thought the image was big - here is the scale! This stuff is best suited to fine detail, not large areas to cover.
This is a thicker window film, it seems to be made of two layers. They are prone to separating.
There is a knack to cutting this. A sticky mat and only use a piece a bit larger than the design so it can be kept secure. Try to get it done in a single pass, which you can if the setting is correct. Don't cut it too lightly though as it will be hard to weed especially if the design is intricate. It probably compares to the Silhouette stamp material.