Adjustable Filament Spool Parking Block

I work and print out of my office in my home. I don't have a garage or workspace to build large spool racks for my filament. I use my existing bookshelf space. So I designed these to be Adjustable Filament Spool Parking Blocks for Shelves. They are adjustable for 2.5" down to 2" and below. They aren't elegant or fancy. They print fast and they work. I just needed something to keep the spools from gradually rolling off the shelf and scaring the hell out of me when they hit the ground. If you need them to hold a larger spool simply scale them up in your slicer. They print well without any type of supports and can be printed in your filament of choice.  They are small, so if they are on a textured surface they work fine 'as is'. If they are on a smooth surface, just a little double-sided tape or something on the bottom helps them stay in place.