An inside peek at my kalax units and what they hold
Kalax 2 x 2 ~ https://www.ikea.com/us/en/p/kallax-shelf-unit-white-20275814/
Kalax 2 x 4 ~ https://www.ikea.com/us/en/p/kallax-shelf-unit-white-80275887/
Kalax 4 x 4 ~ https://www.ikea.com/us/en/p/kallax-shelf-unit-white-30275861/
Kalax 5 x 5 ~ https://www.ikea.com/us/en/p/kallax-shelf-unit-white-70301537/
Stamp-n-Storage for Ikea ~ http://www.stampnstorage.com/#a_aid=dianasoling
(12x12 & 8 1/2x11 paper storage, slim link ink pad holders, drawer units)