In order to understand the basics of three dimensional geometry, we wanted to get some practise. To get the proportions of simple objects right, we built some objects out of paper and arranged them. Afterwards we tried to draw this arrangement with the right proportions.
Our professor gave us a tip which allowed us to achieve much better results: He told us to draw every connection between points, even if the two points aren’t actually connected. He also told us to measure distances and such using our pencil. We found out that holding it with an extended arm in front of us really helped.