I used my Wacom Cintiq 13HD on a Mac in combination with the vector drawing software Clip Studio Paint and Photoshop.
Finished product ready to be send via mail
Printed on thick matte DIN A6 600gqm Paper via moo.com, we had enough space on the (white) back of the card to write personal notes and for signatures on each of them.
They were then send in transparent envelopes via mail to all customers and friends of the agency.