Retractable double-edge razor blade scraper

This retractable razor blade scraper is an improvement over one I used to have for scraping burnt gunk off a ceramic stove top. Features:
* No removable cap to get lost. Snaps into three positions: load/unload, safe storage, blade exposed.
* Sliding the top half all the way back exposes the blade for use.
* The middle position retracts the blade under the top half. In this position the hole on the handle end aligns in each half so the tool can be stored by hanging on a nail or peg.
* Sliding the top half all the way forward allows the two halves to separate, for changing the blade.
* Fits a standard double-edge shaving safety blade.

I have one in my kitchen for my stove top, and one in my car for scraping tree sap off my car windshield. You can use it to remove prints from a glass print bed too -- I don't need it for my Prusa printer because it uses a flexible steel sheet that pops off the prints.

There are two versions:
* `bladescraper_original.stl` is the original design that exist