Shimming bearings use to be a common practice and most auto parts stores stocked shim stock until sometime in the 70's. It is a patch not a repair by todays standards. Just like you can get rings that are standard on the inside to fit the piston but 10 over on the outside to compensate for cylinder wear. Again a patch. Both repairs would allow a cheap way for you to get some extra wear out of an engine but not what you would get from a proper rebuild. Shops don't do it anymore because the customer expects the engine to last like a new one and if the shop installs a reman the reman company has the warranty. Keep in mind that years ago a customer could be told "ok, we will do it cheap but no warranty" and they would be ok with it.
If you want to try it.....
Get the stock that is tapered on the ends. The internal action of moving parts in an engine stretches the caps a little and it compensates for that stretch. Use plastigage, be sure to get all of that plastic off of the journal and bearing surface or else it dams up the oil and you will take a bearing out.
You can cut it with a decent pair of kitchen scissors.
I myself wouldn't do it, but then again I have machine shops close enough that do good work at a fair price and can afford the parts. If you are looking to get by for a few weeks to finish up some work it would be ok too....but as a long term repair??? Might be ok for a trailer queen/parade tractor.