Multimeter calibration DIY - tools needed?

[TiN]

So in theory, a cal lab should be doing a complete, separate performance verification after setting the constants. 

In practice any good lab will do at least two calibrations (which is measurement only of the unknown DUT vs known reference) as received, and calibration as shipped.

Customer may want to have adjustment performed which is separate optional operation, which will go in between two calibrations. Some customers would always prefer to lab never touch adjustments on instruments, since they might be doing in-house history analysis of the device or do other studies, like stability of the instrument under shipment/stress/different labs conditions, etc. By default one should expect that calibration lab would NOT do any adjustments without explicit customer say so.