Filament Spool Bumper

I am completely new to 3D printing and this is my first ever design so it is very basic! (Made on Tinkercad) I designed this model to solve an issue I had encountered when storing my spools in the IKEA Ivar cupboard, but this would work on any shelving or cupboard. The issue I had was that the spools would constantly roll forwards or off the shelf when I opened the door. So I designed this very basic modular bumper which comes in 4 x 18cm lengths. There is a left end piece, a right end piece and two middle sections. To make this longer or shorter, you could simply print more or less middle sections, as needed. As you can see in the pictures, I simply slotted all 4 pieces together, and glued them down on to my shelf, and this keeps the spools in place and prevents them from rolling forwards . You could also use double sided sticky tape or command strips etc. to attach it to your unit if you wanted to be able to remove them in future. This is a very basic idea, and may not work for every