Why don't you like using business cards?

I've seen playing cards suggested, but they're thicker, too.

My questioning of business cards stem from a history of eratic engine runs. Could be the compressability of the material and the potential of shrinkage leading to a loose backplate. Or increasing the crankcase volume too much. The mailla envelope solution sounds like the ticket.  What about RTV    Silicon seal? Anyone use loctite on the back plate screws?

        Peter, I 've been through the same problems as you've been making gaskets and having troublesome issues in doing so. When you get an older engine that has irreplaceable gaskets that's your only alternative. Bob Zambelli shown me in person and has also mentioned this several times on Stunthangar was the use of Permatex. The particular Permatex is the anaerobic Permatex. This product is DESIGNED for aluminum and also for uneven mated surfaces. It was also designed to be taken apart if need be unlike silicone which can be problematic to get off. The anaerobic is solvent resistant and comes in small tubes. They sell a .6ml tube which fits in the field box and will last for several engines. There are hundreds of Permatex products and they're all not designed the same. I've used Ultra high temp silicone in the black and gray and our fuels attacked them both rendering them useless. I've seen the blue work around venturis but the anaerobic works well. It can be purchased in the small tubes for around $5.00. I've seen guys use it immediately after assembly. I let it sit myself I guess I'm just old school. Ken

        Peter the stuff I'm referring to is nothing like what your explaining. In fact when most use the term Permatex, the product your mentioning or the automotive type silicone is what most people are thinking about. Permatex is just a brand name and they make hundreds of different types. It must say anaerobic on the tube. It's red in color and is jelly like. It actually reminds me of the stuff cake makers use to write your name on a cake as it comes out of the tube in a bead approx 3/32" wide. Its very user friendly and like I stated above its meant for aluminum and alcohol. It has virtually no smell and stays in a wet like substance until the mating part goes on. It doesn't cure like silicone does when exposed to air. I'm not sure how to post a pic on here but if you google anaerobic it will come up. This is quite expensive, but you don't need the $20.00 tube. They sell a little 2 1/2" tube that will go a long way for under $5.00. Try this link http://www.permatex.com/products/Automotive/automotive_gasketing/anaerobic_gasket_makers/Permatex_Anaerobic_Gasket_Maker_b.htm  This product can be found in just about any major automotive stores as well. I've seen it online for under$4.00. The main problem with an old Fox.35 is when you remove the backplate, the gasket is pretty much going to rip. I've found putting 3 in 1 oil on them prior to removal and heating works to take it apart but this isn't possible at the field. It isn't always success either. This product fulfills its purpose and for what your paying for it its worth the try as it does come off easy when you do need to remove it. I think its a terrific product. Ken

Neat idea Phil.  About the Permatex - do not use the old brown gooey stuff.  Read the label and you will see that it cleans up with alcohol.  I had to do a clean up and reseal on an old engine after I tried it.