I've read some old threads about this but nothing covering my particular concern - older two are nearly 6 and 4.5 and obviously love crafts, have lots of pens, crayons, various other bits and pieces. We have an art cupboard (bottom of a sideboard) but it gets in such a state. My main worry I'd at they leave e cupboard open and stuff on floor which attracts my 18 month old.
I wonder how people store art/craft stuff for their kids when they need to keep it away from younger children? Even my 4.5 yo can't fully be trusted, she recently used a stamp to stamp ink all over her legs and face 
so I keep the felt tips out of reach in a high kitchen cupboard. But they spend most of their time drawing or making stuff at the moment so something more practical would be useful