Print out or draw the image you want to make into a stencil onto a sheet of paper. This will make your stencil pattern.
Tape the stencil pattern to the back of the acetate plastic with the pattern facing out.
Tape the stencil pattern firmly to the piece of plywood. Use one piece of tape on all four sides to ensure the pattern does not slip while cutting.
Start at the upper left-hand corner of the pattern and carefully cut directly on the stencil pattern line with the Exacto knife. If you are left handed, start at the upper right-hand corner. Try to make each line one flowing cut. Rotate the stencil with your free hand as you cut to keep your cutting hand in a comfortable position.
Remove the tape and paper from the stencil and pop out any pieces of acetate that remain.