The articles listed here didn't quite fit in any of the other "project" categories. They include mostly well-known tricks (great for beginners) and fun, and useful, items to make.

Rocket Building Techniques, Tips and Hints

Fin Slot How-to + Tool
Super Smooth Fins (with wood filler)
Paper Laminate Fins

Rocketry Tools And Jigs

Fin Alignment Tool
Making a mold for a nozzle

Cheap Copperhead Igniter Clip
Build A Rocket Racing Cable
Make A Clip Whip For Clustering

These projects can be built quickly from cheap parts that you can find at most hardware stores.