It seems every workshop has a drawer full of old, dull, burnt, and worn drill bits. There's finally a creative use for them.

When you're working with wood, it's always handy to have a knife around. You can get more accurate guide lines out of a marking knife than you can coerce out of a pencil or pen. It's as close to perfect as one can get.

Shockingly, quality marking knives aren't cheap... and cheap marking knives aren't ever referred to as 'quality.' So what are you to do? Make your own.

The DIY marking knife used to have a gold standard of recycling old dull saw blades... but as blades are rebuildable now, who in their right mind is going to cut up a perfectly salvageable saw blade for a little marking knife? Hence, the brilliant idea to upcycle your collection of worthless drill bits.

Now you certainly don't want to hop into this project with anything high-speed-steel, so I'd start with the bits you know to be junk. Basically, any old store brand bit that sold entirely on a name, and has outlived its usefulness... ei - Ryobi, Dewalt, Kobalt, Harbor Freight, etc... Never waste good, but try to recycle the bad. Good luck.