How do I set up booking for several technicians who each have their own calendar?

The common setup is one calendar with multiple staff. On the calendar's Staff tab, each staff member has their own availability and their own connected calendar. Then on your bookable (the booking service), assign multiple staff so availability is checked across all of them.

If you want separate bookables, for example one for electrical and one for plumbing, create two calendars, each with its own staff member.