Salutations, gentlefolk !
Back in 1970 or so, when 'amateur game design' required a knowledge of Prestype and pasteup and other arcana, I acquired one of these:
which comes apart to look like this
Back then it was known as a 'stencil knife'. It disappeared in the attrition of the decades, and when I retired and found the print-and-assemble buildings of papermodels.at and ships of warartisan.com, I decided I needed another one. So I went to the artists' supply shops of Manhattan and the big box craftstores of Cherry Hill, and was met with blank stares. Drew a picture to my best recollection, no help. Finally, in the depths of the Google, found one for sale, at B & H Specialities of Syracuse, NY – bandhspecialties.com – $6.00 USD for the knife, $5.00 USD S&H.
Unfortunately, t'were out of replacement blades. But the knife's package revealed 'twas produced by Griffin Manufacturing Co, of Webster, NY.
While Griffin's webpage was found, though, an Email query revealed that the #113 was out of production, none in stock.
Well, I shall get an Arkansas stone to keep this blade sharp, though I should _like_ a replacement blade or two in case one goes dull in the middle of a project. Should you find anyone with replacement blades for sale, please get one or two for me, and you shall make a good profit on the deal.
If you regularly cut paper or cover stock or thin cardboard, you probably have one of these. If not, would suggest 'getting one while the getting is good'. If you're new to these, practice on scrap, cutting curved lines, for ten minutes or so, before working on valuable stough. And if there's another maker of these, please let us know.