I've been wanting to make a thin and lightweight case for my Randolph Engineering sunglasses. Sure, they came with a nice hard case, but it's too bulky to really fit comfortably in my pocket, so the glasses often end up in there naked. They are extraordinarily scratch resistant - they proved it by taking a 30 mph dive out the passenger window of my friends car - but I'd feel better about them sharing a pocket with keys and pinball quarters if they had some kind of protection. So, here's how I modeled and printed a lightweight and thin case for them, I'll even include some instructions for 123D Design for beginners to follow along with!
This is my entry to the 'Gadget hacks and accessories' contest, if you like this project please vote! Thanks!
Step 1: The Design - and Some Basic 123D Design Instruction
For a structure that is lightweight, thin, and flexible, I decided to use that old go-to for bees and NASA - hexagons! I used 123D Design (which is free) to model a case from hexagonal mesh. If you're new to 123D or solid modeling in general, this may look like a rather complicated model, but really it's pretty simple. Feel free to follow along with these instructions!
Initial Solid - We're going to make this by creating a solid block and cutting away parts until we have our final case. Measure the footprint of the glasses, then make a flat rectangle in 123D. If you like, fillet the corners for looks or fit. Extrude this upward a few inches, giving yourself plenty of extra space to work with.
Tube Shape - On the right or left side of this new solid, create a new spline sketch and create the side profile of your case. Taking into account the dimensions of the glasses (height and width from the side profile) move the little points along the spline to massage it into the right shape. Once this is made, offset the shape for whatever thickness you want. First I used about 0.02" but this was eggshell-thin and way too fragile. For the second version I used 0.125". Extrude this shape into the block, using the Intersect tool to create a flattened tube shape.
Hexagon Pins - Hide the solids/meshes at the side toolbar, then go back to the original flat rectangle sketch. Draw your shape (here I used a hexagon) on this sketch plane and extrude it upward. Make a rectangular pattern. I had to repeat this process for the hexagon wireframe design, filling in the gaps from the first pattern. Move/position these hexagonal pins to where you want them. Be sure not to let them run off the edges, you want a continuous edge all the way around the tube for strength!
Cut Holes - Go back to the side panel and show all solids/meshes, and pick the subtract command from above. Choose the flattened tube structure as your starting solid, then the extruded hexagon pieces as the second solid (select multiple objects by holding down left-click and dragging across the pins to the left). Once this is done you should have your tube shape with a bunch of little holes in it. If it's all they way you want it, then you're done. Go ahead and use whichever method you prefer to print this thing.
Step 2: Post-Print Finishing
Once the modeling was finished I emailed the file to my friend, who printed it in his suped-up Printrbot Simple. After printing I had a little clean-up to do. This is done easily enough with a hobby knife and some fine sandpaper.
Step 3: Fabric Lining, Final Notes.
A small folded piece of flannel will serve as a lining to keep the glasses from rattling around and provide a little cushioning. This I secured to the top and bottom with a couple of small stitches.
And there you go! I've attached my original 123D file so that you can get a better look at it. If you make something like this please attach a picture in the comments so I can see! And, of course, if you found this instructable to be helpful, interesting, entertaining, or if you're just feeling generous, please vote! Thanks!