art.davidliao.com

I use the Zebra Posi-Grip 0.5 M-1600 mechanical pencil for light sketches and writing equations. It "holds an edge" making it possible to do thick-thin calligraphy. The pencil is very light, but it glides smoothly free of squeaking and scratching. My friends and family hoarded this model from Kinko's about a decade ago before Kinko's became FedEx Office.

Unfortunately these pencils appear to have been discontinued. Here are a couple webpages mentioning it.
http://www.antipoetics.com/junk/pencils.html

Open-source software for doing quick pencil-sketch animations. I use this software to illustrate scientific concepts for my research website http://physics.davidliao.com.

http://www.pencil-animation.org/

Utrecht Art is one of my two art-supply heavens. The main outlet in Cranbury, NJ is a gloomy warehouse. To access most of it their inventory, you give a list to the *one* person at the front desk.

In return for bringing your business to such an "uninviting" place, you get a broader selection and often much lower prices than at Michael's. Michael's prices are so high that for some items you need their 40-50% coupons to get prices competitive with Utrecht's non-coupon prices. That being said, I still buy materials from Michael's when I have the 40% coupons.

6 Corporate Drive

You can draw a three-dimensional cube on a flat sheet of paper using "graphical projection." This video shows four projections including orthographic, perspective, and curvilinear.