Shelf Christmas (or any string light) Light Clip

I got tired of the office christmas lights falling and having to tape it (i really like christmas so I had to fix it lol) I created this to slide on our shelves which are about 19mm wide. THe lights go in on the mouth. Picture shows the right orientation it should be put on the shelf. I can possible be used in other orientations so please let me know if that works)

I've included an openscad file it should be self explanatory and also if the customizer don't like my file. Sure there are bett