the clasp

design The clasp at left is designed from scratch in CorelDraw10 and is based on those seen on Jansport backpacks. When closed, it measures 4 x 2 x 1/2 inches. When open, each half measures 2.75 x 2 x 1/2 inches.

	machining The clasp was cut from 1/8" translucent dark red acrylic and 1/4" opaque black acrylic using the laser cutter. This is the second version, actually. The first one was 3 3/8" layers of dark red. Assembly was done by threading (6-32) the cut holes and inserting set screws. Smaller pieces which cause the prongs to act as flexures are held with the set screws and acrylic glue.
	function It functions incredibly well - opening and closing when you want it to, not when it feels like it. The clasp can withstand people holding onto each end and pulling back. It stays together, but can still be released with an extra hand squeezing the outer prongs as in normal use. As an experiment I cut the same pattern at a smaller size (2 x 1 x 3/8, below) of acrylic. The screws here are 4-40 1" binder screws with the heads cut off. This one opens and closes with less resistance, but is also more prone to opening at the wrong time.
	ideas Before settling on this, I had several other ideas that came up and for one reason or another didn't do: Similar design, using a more durable but still flexible material. These buckles are certainly not made out of acrylic in real life, and aren't designed for its brittleness. Similar design, but using this rotating piece as more of a feature: make it more L-shaped and rotate it in to lock and out to unlock. Any kind of design, but do a cut-out or careful selection of material that signals to the user it's closed: blue+yellow=green or it's locked when the cut-out heart is all red.