Thread: DIY thumb hole A-cat stock for AR-15

Anyone have any info on what the rules are about making your own "thumb hole" A-cat stock for a AR. Everything on the market is either shite or way over priced. It'd be nice to convert a Magpul UBR and still be able to use the adjustable function. I have the design skills and connections to get it made to a high standard so its not going to be a hatchet job. Thanks for any info...done a good search and couldn't find anything