Personalised Geometry Box

A ruler (15 or 20 cm, or 6 or 8 inches), a protractor with a snap-on arm, a 45° and a 30–60° set square with stencil holes, a strip compass and a box with a sliding lid. The child’s name and a small icon go on every tool and on the lid.

Every tool is a 3 mm body with 0.6 mm raised markings. With an AMS or multi-material printer, use the two-colour files in the ZIP (body + markings). On any other printer, add a filament change at 3.0 mm: numbers and name come out in the second colour, and the ticks on the bevelled edge stay raised in the body colour. One colour works too.

Like a real ruler, the ruler and set squares taper to 1 mm at the measuring edge, so the scale sits right on the paper. Reading straight down onto the line is more accurate than reading across a thick edge.

Print the arm pin-up, then push the pin down through the hole in the protractor until it clicks. The arm turns from 0 to 180°; read the angle along its straight edge, which runs through the centre.

Hold the pivot (or pin it with a drawing pin), put a pencil tip through the hole for the radius you want – 2 to 14 cm – and turn. No sharp point, so it is safe for younger children.

The scales are drawn exactly (1 mm ticks, 1° marks); a printed ruler is usually within about 0.2–0.3 mm. That is ideal for learning to measure, but it is not an engineering tool.

Ages 5 and up with an adult. Choose “5–7” for whole centimetres and big numbers, or “8+” for millimetres and a double protractor scale. Not a toy for under-3s.