To create custom size on your Wireless Rollo printer, you need to access Rollo Printer Portal.

Please ensure you are on the same Wi-Fi network as Rollo, then open the Rollo App and visit

Menu > Settings > Default Rollo Printer > Settings

Once Rollo Printer Portal opens, please click on "Media" and choose the desired label size or create a new custom size. 

Click on Save Changes. 

Note: After creating a custom size, you may need to close and re-open the application you are printing from in order for the application to get the most up-to-date sizes available.