I've had good luck with these:
http://www.tickbitesupply.com/case.html#rcScroll about halfway down the page, to these:
DC38 fits: AK, Mak90, HK94, retractable stock AR15, Collapsible Mini-14, and others.
DC42 fits: AR15, M16, Mini 14, CETME, HK91, HK93, and others.
DC46 fits: SKS/FN-FAL/FN-L1A1/FN-LAR/FN49/Sig/M1-A/M14/M1 Garand and many others!!
I've had mine for four or five years, and it hasn't given me any trouble at all. Still looks good, no wear or rough edges. My Saiga loves it, my MAK-90 loves it... my Mosin M44 doesn't fit- so I'll have to buy the longer one for it!
And hard to beat for the price.
Mike