No manufacturer is Currently making a folding stock for the Marlin 60.
Ramline used to, but folks didn't like paying $89 for 'em.
Sometimes you can find Ramline stocks on auction sites...if you find one for either the Model 70 or Model 60,
If you get a Ramline 70 stock, you must cover the mag well hole and drill a hole in the tip of the forearm for the mag tube.
If the stock is a Lockarm version, you get an ATI SKS Retrofit kit and install it, making it a folder for $10
I do know some folks are working on making a more modern folding stock,
but it'll probably be next year before they hit the market...