A customizable modular storage unit organizer apparatus with a pair of slides, a pair of slide covers, a pair of cross bars, a pair of retainer clips, and a container for storing articles within the apparatus. The cross bars extend between, are affixed to the slide covers, and have two distal ends, top, bottom, first and second side portions, a slot extending longitudinally along the length of the exterior surface of cross bars for accommodating attachments. The retainer clips allow the slide covers to be selectively, repeatedly, and releasably retained to the slides. The size of the enclosure formed between the slide covers and cross bars may be modified by adjusting the positions of the cross bars on the slide covers.