Fender used to use a Hammond verb. You could probably get one and make your own outboard device. You could put it in an effects loop but you'd have to work out a blend since you would not want 100% wet. Maybe a wye cable and a volume pedal or something.
__________________
"I believe that entertainment can aspire to be art, and can become art, but if you set out to make art you're an idiot."
Steve Martin
Show business: we're all here because we're not all there.
Resistance is not futile. It is voltage divided by current.