Yes. The only way your protected, at least temporarily is through patenting. Because what you license is the patent not the device.

You can develop a sort of drop shipment operation if you can find a manufacturer in this field who can build t and operates with a Just In Time approach... They build as orders (from your sales efforts) come in, and they take care of shipping to client, not you (drop shipping).

This is a better approach as you can sell something you currently don't have in stock, or have to spend as much money on patenting before knowing if there is really a demand.