A Pencil Cup (6/17/2020)
The PCB layout. Traces were drawn for aesthetics over perfect function.
The final CAD model of the pencil cup
Recently it was my friend’s birthday, and I wanted to make her something. I’m not usually big on birthdays, but wanted do something this time. We had been talking about things that she needs, and it turned out she didn’t have a pencil cup for her desk. Personally, I thought that was pretty odd since she’s a writer, but I didn’t question it too much and set off on designing a pencil cup.
I started out with some sketches of different ideas, but didn’t really like anything I came up with. A little discouraged, I decided to play around in CAD and see if I could come up with any cool ideas there, which proved slightly more fruitful. Ultimately, I ended up looking online for inspiration and found a desk organizer from IKEA that I liked. With a mental image, I started sketching again, and finally made some progress.
I decided early on that it should be a very unique pencil cup, and that since none of the parts needed to be perfect or have tight tolerances, form could take over a bit. To meet the uniqueness goal, I made it out of several materials, and gave it some flair with LED’s. The final design slowly came into form, and I got to work making it. Although I wouldn’t call it much of a cup anymore.
The outer shell is an SLS 3D printed part, which gives a great feel and a striking look thanks to the slightly rough texture. The bottom of the cup that the pencils rest on is a custom PCB with 22 blue LED’s on the underside, and channels routed out of it to let the light bounce back through. The channels would then be filled with a clear casting resin to give the PCB some reinforcement, and provide some light diffusion. To provide power to the board, I debated batteries, but decided that rechargeable batteries would take up too much space if the battery life was going to be a few weeks, and coin cells wouldn’t last long enough and aren’t exactly cheap to replace, unless you buy in bulk. So I settled on a USB port also on the underside of the board.
The final pencil cup is really nice. It makes a statement while looking subtle, and neither of us had either seen a pencil cup like this before.
