It never fails. Just when you need a certain gasket either the stores aren't open or they don't have one to fit. Worse, you just ruined the one gasket you had, and now you have to stop the project.
Not to worry, however, because you can make your own! Right now, before you forget, run down the to auto parts store, hardware store or small-engine repair shop and buy some gasket material. You can find all sorts of gasket materials, from cork to composition, fuel-resistant to metal. It comes in sheets roughly the size of typing paper and frequently can be found in sets that contain an assortment of common materials.
Okay, now you have the gasket material and you've selected the proper sheet for the job at hand. How do you cut it? Carefully, that's how, but not as carefully as you might think. After all, the holes through which the fasteners go don't have to be beautiful do they? Here's what to do...
If you have the old gasket, use it as a template to draw on the new material. If not, place the material on the surface of the part and gently — gently! — tap on it to create an impression of the holes and passageways on the underside. If you have a copier and the part is small enough, put it on the glass platen to make a paper template for the gasket.
When drawing, use a very sharp pencil or even an Xacto knife to make accurate lines. Drill fastener holes with appropriately-sized bits, preferably Forstner bits. Cut passageways with a new, sharp razor or Xacto blade, taking your time to get a nice sharp edge. You can always lightly sand rougher edges to make a smooth opening.
There you go! Keeping an assortment of gasket material around means you'll never have the problem again.