I needed a stitch holder (or rather 5 of them) for the blanket I am currently knitting.   I was inspired by the lockable stitch marker by osoderholm.  The trick was to make the print thick enough that it could hold up to a bit of abuse (heavy project, getting tossed in a travel bag, etc.) without breaking and still flexible enough to open and close.

I have been through a few iterations of this project, and it works--up to a point.  I want it to stay closed a bit more securely.   I could not make the lock stay closed more securely without needing to print it with supports.  In the end, I have been using a small rubber band to ensure that it stays closed even when I throw it in my travel bag.  

I look forward to someone fixing the problem for me.  In the meantime, this should work for anyone who needs a quick stitch holder.