I use Pop-Can aluminum for all kinds of gaskets. It is easy to do. Using scissors or garden shears (plenty choices in the $ store) cut an oversize piece of material. Lay it over the place it is supposed to go. Firmly, (use thumb/finger) pressing over the area against the engine. You get an outline. Be sure get an impression where the screw holes are.

Then using a sharp Xacto or such, cut out the inside portion. Drill or cut the bolt holes. Easier to stick and cut with Xacto then sand off any burs. Bolt it on and use knife or shears to trim off excess. Been my way for many years.