You may be right and I wish the best of luck. My concern is that you may be be offering too much at one time?

If I was designing such a seminar, I might offer different sessions for each make so that a prospective owner could learn how to operate, trouble shoot and calibrate "his" printer.

Actually we have been quite successful doing just that. My son and I run weekend seminars where we give the participants a box of parts on Saturday Morning and they go through a step by step process of building, calibrating and printing with their own printers. Sunday afternoon they leave with their assembled printer, all calibrated and several test prints that they have printed on their own printer. We have a 100% success rate but do not cover any design/slicing software.