razor blade scraper with cover and retention tabs

Razor blade scraper for getting under prints. Adds locking tabs to the original model, as part of the holder body and on a slide-in clip that engages the outside notches on a double ended razor blade to retain the blade so that it doesn't come loose when you pull back to recover. Includes slip cover for safety when not in use.

UPDATE: I have a redrawn version with a better blade retention mechanism here: http://www.thingiverse.com/thing:697672
Give it a try if you want to make sure the blad