A mechanical adapter that lets you use attachments designed for the Hitachi Magic Wand with the much smaller Lovense Domi. Should be printable without supports, especially if your printer has a cooling fan.
This is a work in progress, so please share any feedback you have! It should fit nicely, but if not, scaling the part up or down by a few percent could help. If it's too loose on the Domi, a rubber band around the groove will keep it on.