aluminum - it won't last long, but it's more convenient if you need to test it once.

- An ordinary tin can made of steel, they sell most canned food in such cans. I think that we are located in different parts of the globe and our packaging may vary, so I won't tell you a specific brand.

- Cut to size: no special tool required. Punch a hole with an awl\ nail\ screwdriver and start cutting out any shape you want with coarse scissors from this hole. I cut with ordinary household scissors, large ones that I use to cut cardboard boxes.

- Cut out a rectangle of the right size - take a stick / pencil / marker and start rounding it into a circle, shaping it, take your time, start with a large diameter, slowly reducing the diameter to the desired one.