I have a pen-plotter! It’s great. It’s like having a printer but slow and it breaks more often. I got it on eBay and it came sorta broken and I immediately spent the difference between what I paid and the price of new one fixing it. Now it’s fixed! My favorite thing to do with the pen plotter is to create things that I wouldn’t be able to create on, say, a printer, or by hand. 1 Sometimes that’s because the medium is different; for example, these gold ink postcards I made of an Iguanodon fossil : But recently, I’ve gotten excited about using the pen plotter to make holograms. You could derive hand-drawn holograms from scratch William Beaty has an amazing page 2 about how to make holograms by hand and it includes intuitive explanations of the optics behind them. You can read this page for an awesome explanation of why hand-drawn holograms work and what makes them so effective.…