If you're a parent whose kid likes toy cars, you've probably got toy car clutter. A cheap, DIY solution to ditch that clutter: A shoe rack.
A Lo and Behold Life offers a tutorial for converting a basic shoe rack into a toy car wall display. Basically, you attach two of the shoe rack shelves together and hang the whole thing on the wall. This should work for Thomas the Train collectors and other small toys like these. (I might have to do a version of this to put an end to Skylanders figures taking up my living room.)
I couldn't find the exact rack shown above for sale online, but there are similar versions, like this $US14 one on Amazon, you could use for the same purpose. Or if you don't want to do the DIY yourself, A Lo and Behold Life sells a customised version of this project, first seen at PJ Toy Car.