I am bringing you a dual tracking power supply, a 1980's vintage Hewlett Packard power supply.
One knob could do with replacement, and one of the meters has been pushed in, but these are cosmetic issues only. I have tested the unit and it is within spec.
I will also bring with me a very accurate 10V source if anyone is interested in checking their multimeter. The cal certificate says 10.0000041 VDC (0.4ppm error). It actually takes about 2 hours to settle to this value, but unless anyone has a 6 1/2 digit (or better) meter this won't be an issue.
Oh, I also have some very accurate resistors for checking resistance ranges.
And of course I have some small samples of what I've done on our laser cutter using my software.