I won't pretend there are extensive art supplies in this house, because there aren't! I find most immediate crafting urges are met with my little wooden tray above.
It is actually an Ikea cutlery tray that doesn't fit in our kitchen drawers as it was intended to. Here is an image from Ikea's website, as my pic above is a bit arty (Queen of Clean was teaching me depth of field) and doesn't show great detail.
On one side we have 2 enamel buckets (bought ages ago from Sainsburys - they were 99p each from their summer garden range) with scissors, pencils and crayons in. I will confess that I avoid felt tips at all costs due too many incidents of 'unauthorised' colouring of pine chests, walls, oak tables......I am fairly laid back but in the end the felt tip pens had to go..........
On the other side we keep sellotape, pencil sharpeners, pritt stick, PVA glue, spreaders and whatever other little crafting doodads we have picked up...wiggly eyes and the like.
This little system has meant everything is to hand immediately for that impromptu creation, and has saved lots of frustrated cries of 'I can't find the sellotape' (Why is it that they need sellotape for everything?). The tray lives where all the children can reach it, on the bookshelf in the playroom.