I can make a shovel or pick myself if need be, but since it's cheaper, faster, and easier to buy one (made by those who do it faster, cheaper, and better than home-made), it would be silly to make a home-made one.
I have actually made home-made carriers for magazines and even for revolver speedloaders, but factory-made ones are generally preferable. The one thing I do still use some self-made versions of are handgun holsters. The cross-draw for my SRH, an 'avenger' style one I made for my Detonics years ago, etc. But even those aren't overly cost-effective when compared to factory-made, taking several hours each.
Just as you often point out about reloading, the time involved often makes it not a good return on your investment.