Any cheap alternatives to the plastic stencil sheets?
Masonite is too thick to work with. If you're doing street art, you still kind of want to be able to draw like you can with an exacto. Plastic sheeting is good if you want to be able to reuse a stencil. It also rolls up. But cheap poster board works just as well, except that it can fold, which you don't want. You can always go back and cut the plastic stencil from the poster. If you're dead set on the plastic, but can only find 8.5x11, just use clear scotch tape to match the edges. Just make sure the cut outs don't sever the whole seam. Poster board will tear, so let paint dry before you lay them down, and lift them off the painting surface before they dry
Make a stencil of a powerpoint with plugs I have one and it looks really cool
A couple ideas of the top of my head -Masonite is super cheap, light and durable composite wood (if you're still going to use a jigsaw to cut the shape) -really viscous acrylic paint (make sure to put vaseline coated shapes in where you want your spray paint to go through -card stock + knives
