So you have a radio, tube tester, signal generator, etc. with the flat leather handle rotted off.
So what do you do? Go online & try to find another good original handle & pay big bux for it?
Nope. Not me. I just go to the local charity store and find a GOOD REAL leather belt that is close to the correct width & thickness I need. A couple of cuts and Viola! a custom made handle, almost or identical to the original. Nice thing is you can cut the "arrow points" on the ends , dye it, or sew 2 or more layers together to get the right thickness.
Now if you have a saddle maker nearby, you might be able to score some cheap trimmings for a really tough leather for the handle.
The leather can be dyed by any shoemaker worth his salt too. They have a sewing machine tough enough to easily sew thru several layers of leather for the thicker handle.
Last custom sewed one cost me $5.00, his minimum charge, and he dyed it black gratis!
Leather does come in various thicknesses/ weights. You might like to go online and research the thickness/ weight that will match up to what you need if you order it online.
Treat the leather with a special leather preservative oil too. Remember too much Neatsfoot oil will turn it soft and soggy. There are others that work better than Neatsfoot oil.
I have found "salvaged" leather belts to be very useful for replacing on trunk handles, tool boxes, etc. also.
Typically, a used, real, solid leather belt should run just $2-3.00, and provide you with enough material for several handles. I find the longest ones I can and as wide as I can find, as it's easy to cut down the width to what you need. Be sure your cutting tool has a very sharp blade, as it makes cutting the leather much easier.
Look closely, as some are faux leather made from a micro thin layer of leather and glued to vinyl. Useless for handles, as they have little strength, and will crack and break pretty easy.