As someone who stupidly committed to laser cutting 30-odd spirographs for my four year old's birthday bag treats last year and ended up realising what a stupid

As someone who stupidly committed to laser cutting 30-odd spirographs for my four year old's birthday bag treats last year and ended up realising what a stupid idea that was for that age group - you need to go with ball-tipped pens, be they Bic Biros or whatever. Crayons are useless, felt tips are too grippy and even pencils aren't much good, as there's too much friction, especially when the hole size is quite tight.