Making a Hardened Leather, Hinged Eyeglass Case

With the leather hardening technique refined and hinge designs established, it was time to put them together for an all new piece to show off the methods. I chose an eyeglass case for being simple, common, and a good application for both of these. Finished photos first:

Top side

It’s a little rough given it’s my first attempt, but I’m very happy with the results. The case is very strong and affords plenty of protection. The hinge mechanism works perfectly. Future pieces will be lined with foam and fabric on the inside, and dyes and improved molding & finishing will enhance the aesthetics.

Building a molded piece begins, of course, with making a mold.

Lately I prefer to design a new piece on graph paper, then transfer to the actual medium.

Two molds were made, since each case consists of two halves. I made each mold 1 cm taller than each finished half, to allow for creation of the hinge.

One mold is completed.

Leather is soaked in lukewarm water for a few minutes, then shaped by hand to the mold before being clamped in place to dry.

Templates are designed and cut out for creating the hinge on the back of the case. Click here to see the hinge design process.

Once dried, the case halves are paired up and trimmed to fit. Getting the halves to match up properly while not interfering with the hinge function was tough. I used a belt sander to try keeping things flat, and the hardening process allows for some encouragement to fit properly, but I did end with a few small gaps. On the next case, I plan to trim far less leather initially. I’ll approach the hinge first, pinning it while open. Then, I’ll gradually bring down the edges of the case halves to ensure a perfect match when they reach the correct size.

Holes are drilled for the hinge pin before hardening. It can be tricky to ensure the drill bit doesn’t wander out the side of the hinge knuckle; go very slowly and guide the bit through the leather with your fingers.

The hinge pin channel ends on the inside of the case. The pin tips will be bent over, and will eventually be concealed by a liner.

The hinge pin is carefully inserted. For this first piece, I used a random piece of wire. For future pieces, I’ll likely use piano wire.

The “X1” hardening method is applied- the leather is first preheated to 150F…

Then immersed in molten stearic acid at the same temperature, and then placed back on the heat to about 200F for around thirty seconds. I overshot my target this time, but still ended with an excellent material.

After removing the case from the stearic acid, I immediately began wiping excess off the leather, and when somewhat cool, wrapped in plastic wrap and then duct tape while maintaining good shape and proper alignment of the case halves. The case was then placed in the freezer to cool and harden.

Fifteen minutes later, the leather is extremely rigid. The edges were given a final sanding, and a strap added for closure. Stitch holes in the hardened leather were drilled.

A Sam Browne stud was added to the strap before stitching on. After adding the strap, this case would have lining added to the inside and then considered completed.

Thank you for reading!

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