So I'm having some issues finding a good solution for this hinge lock, we need a fastener that will hold the joint at 100% closed. What would be a cost, assembly, and design effective solution?

Here's the details, thanks in advance for the advice guys!!!

The hinged blocks are delrin, the center block is aluminum. The fastener needs to remain locked while being vibrated, jostled, and dropped. The solution needs to be safe as the product will be under light spring load but could cause harm if the fastener failed. The fastener needs to be quick and simple to lock and unlock (quarter turn or so). Threads could be tapped into the aluminum or delrin if needed. The fastener will remain in place for continual locking and unlocking, and should not protrude outside it's hole. A hex head bolt would be preferred. While under a load of less than 5lbs of resistance.

Here is a {concept} file for viewing, and here are a couple fasteners I was looking at:

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(the above fastener looks like a great option but doesn't have a way to thread the receptacle into the aluminum.)

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(the above has a threaded receptacle but way too expensive a solution and the dimensions don't work)

i.froala.com

i.froala.com