Bill
Almost anyone who is handy with a lathe can make caps to fit. I am not really handy with mine but have managed to make several sets, although they don't look exactley like the orginals. They do serve the pourpose well of protecting the lens. A somewhat time consuming job between threading and knurling a small area. It seems also the caps will not interchange between brands although the thread pitch is the same.  It seems almost necessary to custom fit the caps to each scope. I do have one orginal objective cap(aluminum)  off a 1 1/8 inch model if interested.

Tom

Some camera lens caps, also some binocular & spotting scope caps, are the same thread sizes as some of the target scopes. I have used the threaded cap from the eyepiece of a cheap BSA 1" variable as the cap for the objective lens on a !" Target Unertl, for instance. I had to reshape the knurled portion since it was quite 'agressive', but a little spray paint, cured in the oven, made everything look kosher. Not as good as steel but better than nothing.
Good luck, Joe

I just cut a groove on the inside edge of the cap and thread into the recess. .820 length of thread sounds like a lot, the orginal caps only had about 4 turns of thread. I made mine longer and just faced off till I had what was needed. Tom

Sorry about the thread length error it should have been .082. Upside down and backwards sounds good. I may try that. Thanks.
Bill