Paper gears need to be flat to work properly, here's how to make sure your gears come out correctly. The gear I will show you is the 23 tooth gear from the Mesh Gear Crank.
Cut out the rectangle containing the gear and fold it in half. Spread a thin layer of glue evenly on one side of the card. I use PVA – white school glue
Fold over the card and rub the two halves down firmly over the full area of the side.
Put a couple of sheets of card down onto a flat surface such as a cutting board on a table.
Lay the gear in the middle of the card and place a couple more sheets of card on top of it.
Weight the resulting sandwich down with a heavy book.
Leave the gear to dry for at least half an hour. If the sandwich card appears to be damp it is worth swapping it out for a couple of new pieces and letting the gear dry for a further half hour or so.
Once the gear is completely dry, carefully cut out the spoke holes…
…and the hole in the centre of the gear.
Using the sharp knife, cut along the bottom of the gear teeth.
Cut right round the outside of the gear.
Then, with your scissors, cut out the rest of the teeth.
One gear, ready to go!