Here's what I've done to it:
You will need to drill a second hole through your blade, a carbide drill is excellent but I guess you could manage with a small Dremel tool and grind a hole through.
You will need two 6-32 by ½" screws and nuts to hold everything together.
You might have to file away at the cavity a bit depending on the blade brand you use. For me, Lennox blades drop in whereas I had to fiddle a bit to fit the Diablo pruning blade you see in the photos.
Printed flat on the bed plate using just a bit of support in the blade recess. Mine was printed with Polymaker PLA, .2 layer height and I used the fuzzy skin option in Cura to help with the grip.
EDIT: There's also a sheath for this little saw:
https://www.printables.com/model/392439-sheath-for-the-saber-saw-handle
The author remixed this model.