Many moons ago I acquired a JC Higgins "Model 20" 12 Gauge 2.5" chamber shotgun receiver through questionable means (on ebay, of all places). Not being a shotgun guy, it was really tough trying to find what model this shotgun was with just an unmarked receiver. To add some confusion, it should be noted that this shotgun was also known by other names including "Flight King", "High Standard", "Sears", and 583.XX (Where XX is whatever random-ass number Sears decided to use at the time).
It was missing the barrel and stock, but was otherwise all there. I bought the barrel off Numrich, but could never find a stock (for less than 50 bucks), so I made one from a broken Gewehr 1888 stock I had lying around. I simply drilled a hole all the way through the length of the stock, ran a threaded rod through it that connected the receiver, and tightened it up with a nut (at the time, had I known how rare Gew88 stocks were I would have saved the fore-end and made the simple repair to restore it). I finished it with some gloss black and called it done. It was a little short and uncomfortable, but it worked.
I added a B-Square Universal Rail Adapter for ribbed shotgun barrels and a Walmart BSA Reddot Sight (more like a red BLOB sight, am I right?). I became annoyed with the stock so I replaced it with an ATI universal folding stock, not knowing if it would fit. It came with adapters for common shotguns but nothing for old stuff like this. I used a Dremel to chop a Remington stock adapter and even though it's not quite smooth-looking, it's still pretty solid once you tighten the screw. Oh, and since I never really thought about it, I ended up making the grip too close to the trigger. I forgot what the thing is that's attached to the trigger guard in the picture, I think it was called a trigger pull extender, or a trigger boot. Basically it moves the trigger away about 1/3" and also lightens the trigger pull, but it feels cheap. The aluminum shells on the holder are cartridge adapters for shooting .357 magnum and 9mm. I got case head separations from the .357 magnum adapter while shooting light .38 special rounds, but steel cased Wolf in 9mm worked pretty well and is pretty accurate... But that's a story for another day.