Blue sharpies are faster and easier than Dykem for small layout work.
I keep an assortment of various sized washers for layout work. If you want to drill holes in the corners of a square plate 1/2" in from all edges a washer with a 1" outside diameter will put the center of the washer at the center of the hole. Way easier than measuring.
I use the washers for layout of lightening holes as well, usually on the aforementioned chipboard.
Automatic center punch.....get one.
Kwik Scribes are worth their weight in gold. https://socalsac.com/tools/kwik-scribes
In General, Minimum bend radius = material thickness = material used to make the bend. A 90* bend in 16 ga (.063") will "use up" a 1/16 so cut your blank 1/16 big.
Measure twice, cut once. Never "burn" an inch when using your tape measure, it always ends badly. Also make sure the hook on the end of your tape is straight and square.
A 6" piece 3/8" rubber fuel line slipped over the porcelain on your spark plugs makes installation and removal easier around headers when you can't get your fat fingers in there.
Always torque your wheels immediately after installation.....always.
You can use the open end of a wrench as a caliper to measure round stuff. Not sure if that bolt is 1/2" or 7/16" grab a wrench and find out.
When making brackets for various items, always radius the outside corners and then deburr them. Sharp corners under the dash can cut wires, hands, and foreheads.
Take care of your hands. This is right up there with safety glasses and ear plugs. If your hands are dried and cracked they don't work as good and little scrapes and cuts that aren't usually a big deal last forever when you work with your hands all the time. Your wife/girlfriend/sister/ mom has at least 10 different kinds of lotion, steal some and use it......on your hands. I wear gloves whenever I am working with metal.
Good thread, Greg. Should be all kinds of neat ideas come out of it.