I have a full vintage B&K 2209 SLM kit right here, with a 4220 pistonphone. OP is probably thinking of an electronic calibrator, being easier and cheaper. I think we are talking old-school field calibrators here, good enough for a quick check in the field, but only at one frequency and level.
As mentioned, after designing a suitable microphone adaptor/coupler, the trick will be calibrating the calibrator. I think the electronic calibrators basically just have a little speaker and oscillator feeding the adapter/coupler. For hobbyist level confidence, I think I might just try to borrow a calibrated SLM and go from there.
This pistophone largely predated the electronic calibrators IIRC. They require precision construction. This one resembles the handle of a D-cell Maglite (or the handle of a lightsaber). The coupler, for 1/2 inch measurement mics, slips over the mic capsule and is sealed with an O-ring. There is a little chamber in front of the mic, and 2 tiny plastic pistons move in-out into the chamber, driven by a central cam attached to a voltage regulated DC motor. It says 124dB. No frequency mentioned on the unit, but I recall it being around 400 Hz. I assume the volume and dimensions of the chamber make a difference depending on the piston size and travel, etc.