Create custom inventory system

We are a small t-shirt shop and would like to build a mobile friendly inventory system. This system should integrate with our shop management software Printavo (documentation https://www.printavo.com/api/docs). The ideal system would generate a 2″ x 4″ label using a Dymo 400 Turbo label printer when the work order status is changed to preflight. The label is already generated within Printavo and should be used since it’s used in other processes throughout the shop (we can change the format of the label as long as the QR code is intact). We would scan that QR code using a phone or tablet camera and it would populate a list of items that are needed. The user would then enter how many of each item they’ve pulled. Each item number has multiple sizes. The shelf label with a QR code should be different for each size. The system would also need to have a field where we can mark if we are short and how many so our purchasing agent can order the necessary items. It would also need a low stock threshold and email notification if the stock is low. There is an option with the API to generate a PO within Printavo. This would be helpful but an email would be fine for version 1.

The system would also need to be able to generate the shelf labels with QR codes.
The system would need to be able to do cycle counts by scanning the shelf QR code and then entering the count.

We also don’t just deal with shirts, but other items such as coffee cups, tumblers, etc. that are just a single size.

This system would be hosted on a subdomain through our web hosting provider.