Design parts that fit and print well: dimensions and walls, clearances between parts, which way up to print, and the slicer's trade-offs between time, plastic and strength. Each idea on a board first, then in Tinkercad and on the printer.
Each lesson works two ways. Students can work through the online tutorial at their own pace (it checks their answers and saves their progress in their browser), or you can teach it to the whole class from the slides, then send students into the tutorial for the Modify and Make steps.
Every lesson guide has plain-language notes, the answers to every check, a solution for every task, and slides and a worksheet for Waypoints Prepare. These guide pages are not linked from student pages, but they are not secret either: keep printed Teacher editions for answers you do not want students to find.
Whole-course cheat sheet: Open to print (every command, grouped by unit: a handout for the final challenge)
Dimensions and walls, and clearances so parts fit.
A design is a set of dimensions. A box has an outside size and a wall on every side, so the inside is the outside minus two walls. Something that goes inside needs a gap around it.
Parts that fit together need clearance: a hole slightly bigger than its peg. Drawn the same size, they won't fit once printed, because a 3D printer squashes plastic outwards: holes come out about 0.2 mm smaller and pegs a little bigger. About 0.2–0.4 mm of clearance gives a sliding fit; less is a tight press fit. Every printer differs, so print a tolerance test card once and record what fits.
dimension, wall thickness, clearance, tolerance, press fit, sliding fit.
Cheat sheet: Open to print (A4, with board pictures) · Markdown
Which way up, and the slicer's settings.
A printer builds a part in layers. Each new layer needs something underneath it: an overhang more than about 45° from vertical needs supports, which waste plastic and leave rough surfaces. Layers bond less well than the plastic within a layer, so a part is weakest across its layer lines: turn it so the load runs along the layers.
The slicer turns the model into layers and settings. Layer height sets the finish and the time (halve it, double the time). Infill fills the inside; past about 20–30% it adds lots of time and plastic for little strength. Walls (perimeters) add more strength for less.
layer height, overhang, supports, infill, walls (perimeters), slicer.
Cheat sheet: Open to print (A4, with board pictures) · Markdown