This is extremely easy and cheap. I´ve seen these types of organizers for 150 pesos (13 dollars) In my case, this was completely free since I used scraps and foam sheets that I had lying around. If you want it to be larger, just add more foam.
by Guidecentral English
by MiltonCor - MyDrawingTips
by SHINANDA_CLAY
by HowtoDrawAndPaint
by sravya gangone
by ALWAYS_BARTAMAN
by 3D4Kids