I like the idea of grouping collectibles together in an interesting display. This way those things that make me smile when I look at them aren't squirreled away where I can't see them. This way I could see them daily for a smile.
Buy an IKEA shelf and either (a) talk about how disgusting you feel for feeding the capitalist conglomerate or (b) insist that it was your grandmother's shelf and scratch it up really well before putting display items on the shelf.
I love leave cube shelves, but knowing how I do things it would be obliterated by stuff and loose any decorative attraction...its better for me to put clutter out of sight or keep in control of things and then I don't need to worry about where to store things