Below is a list of some tools I have found useful while scratchbuilding. Some of these I already had because I have machine tools, but have been very useful for building my plane.

1. Magnets- Neodymium magnets work great for holding parts together for doing test fit ups. Wrap magnets in duct tape with extra hanging off as a tab to grab onto them.

2. Steel sheet- Laying steel sheet on my workbench and magnets to hold aluminum and layout tools in place. I use  20 gauge ungalvanized sheet. If I had it to do over again I would have bought galvanized.Deburr and wrap all sheet edges in tape to avoid scratching aluminum.

3. Two meter long meter stick-Excellent for laying out longer lines. I actually have two and lay them end to end for laying out full sheets.

4. Machinist parallels- Great for drawing  tick marks and doing right angles in tight locations.I also use these to align bending site lines to the nose of my bending brake

5. Drywall square-Probably everyone has one of these, but the downside is it can only be used from the edge of a sheet of aluminum.

6. Big triangles- I have lots of little triangles, but there are large plastic triangles for sale that work nice for larger layouts. Be sure to verify accuracy of triangle when you get it.

7.Gage Blocks-These work nicely for laying out short distances or offsets from other lines. Used for laying out center lines between holes after they have been drilled

8. Surface Plate-Goes well with the gage blocks for layout lines on smaller parts. While I would like a large surface plate, my little 9x12 inch surface works quite well and can be carried.

9. Surface Height Gauge-Used with surface plate. This actually is not as useful for airplanes since you do not want to scribe lines in aluminum. However I do use it measure dimensions of parts that I make. I do sometimes use it for layout, but only when drilling larger holes where the scribe marks would get drilled out anyway.

10. Dowel pins-The primary use is for aligning forming blocks and blanks. At first I was using screws to hold form blocks together. However holding form blocks together is really the job of the clamps. I use 1/4" diamater, 2 inch long dowel pins. The extra length is to allow a pair of pliers to pull the pins out. The pins are hardened. I have yet to scratch one pulling it out.

11. Optical Center Punch- This is for getting a punch mark in exactly the right location. It would be overkill and time consuming to use for rivet lines.  It very useful for getting an accurate mark for various brackets and control arms.

12. Screw driven adjustable height table- This has worked great for getting tools at the exact height to a table. The hydraulic ones are cheaper, but the tables that use a screw are easier to set the height and don't leak down.

13. Makita 3/8" belt sander- This is a 3/8" wide belt sander. This has been quite useful for removing saw and cut marks from metal edges. The speed of the Makita is variable and allows better control of material removal. There are air drive equivalents as well, but I have not used them.