Step 1. Transfer design onto adhesive plastic sheet
Using carbon paper and a pen or sharp pencil, trace over your design onto the backing paper of the adhesive plastic sheet.

Note: You are tracing on the reverse side, so make sure your design is the opposite way to how you wish it to be on your mirror.

Step 2. Cut out stencil
Using a sharp craft knife and a cutting board, cut out the design to create your stencil.

Step 3. Stick adhesive plastic in position on your mirror
Peel off the backing paper on your adhesive plastic sheet and ensuring your cut-out stencil is in the correct position, stick in place on the mirror. Be sure to allow a lot of excess plastic paper so you have plenty of room to apply your etching acid without affecting other parts of the mirror's surface.