The most important tool for general purpose is the coffee maker.
Nothing beats a nice cup of coffee during work.
No really, the first most important tool is the safety glasses. No
job without it.
The Dremel is a real multi purpose tool. Drilling holes, sanding
models, cutting track, use it on brass, the uses are endless.
The glass fiber pencil, or a glass fiber burnishing brush.
This
tool has many uses, e.g. cleaning contacts on circuit board, cleaning
brass, and removing paint or rust. Any way a nice little "got to have
it" thingy.