If you want to calibrate test equipment (like multimeters) you can buy a calibration standard (which you must then have calibrated regularly) and check all your meters against it.
Unless you've got a lot of meters it's cheaper to just send them off to a local calibration lab !
As for checking the calibration of medical equipment, I wouldn't trust a piece of equipment which had been sat in a cupboard for a couple of years to be an accurate "standard" to do comparrisons against. That also sounds like a very expensive way of achieving the desired result - or not, as the case may be !
