What tools do I need to build a balsa bridge?

Short answer: a hobby knife with spare blades, a sanding block, a metal ruler, pins, a flat board and a small scale. Everything else is optional.

Essential

• Hobby knife and a pack of new blades. Sharp blades make clean cuts. See cutting balsa.
• Cutting mat or hard flat board.
• Sanding block with fine sandpaper, or sandpaper glued to a flat block. See sanding balsa.
• Metal ruler or straightedge, to guide cuts and measure.
• Pins and a board you can pin into, to hold sticks on the plan.
• Wax paper, so glue doesn't stick the bridge to the plan.
• Glue. See which glue.
• A scale that reads to 0.01 g, for weighing sticks and the bridge.
• Pencil, for labelling pieces.

Nice to have

• A cutting guide or mitre box for repeat angles.
• Small clamps or clothes pegs, to hold joints.
• A needle or toothpick for applying glue.
• Safety glasses for testing.
• A square, to check that trusses are straight.

Check the rulebook: some on-site contests limit the tools you may bring.