1. The Primera
Macaron adapter kit can be used to print on Macarons using the carousel tray or any object that would otherwise be too small to fit on the carousel tray. For Macarons, the hole in the center of the adapter prevents the Macaron from wobbling/rocking/moving during printing.
Follow the instruction video below for details.
2. There are third party custom trays that also allow you to print on Macarons.