The latches have always been the weak point on my frequently used tool sets. This latch will fit cases from all of the major tool vendors, but you'll never see it available separately on the tool truck. The example shown is on the case for a Snap-On tap and die set.

I had my best success when printing "upside down" using support material, The overhangs for the snaps print much better this way. Printed in ABS using 100% infill with 1 shell. Make sure that you heat them to soften them adequately before installing. They snap-on perfectly and secure the case better than the originals.