I never heard of Jetpens before but I'm excited to see they sell what is essentially colossal, unbranded Altoids tins https://www.jetpens.com/Velos-Tin-Pen-Case-Wide/pd/14193
western equivalent would be trapper keepers with their pencil pouches.
Would recommend. A little plastic box that prevents me from having to fish around in my backpack possible get poked when I want my pencil is great, and they are pretty cheap.
Compasses, dividers, protractor, setsquares (that we don't use these days) and a 15cm ruler. Pencils, sharpener, rubber. Usually a stencil for lettering and a leaflet with geometry definitions.
Available from supermarkets, stationers and cash and carrys right now because it is GCSE Maths exam time.
back in high schools I had a zen micro mp3 player that fit snugly inside an altoids tin, drilled a hole for the headphone jack and felt pretty stylish.