Contactless payment

Here it is best to contact the manufacturer of the vending machine on this issue. It is unlikely that the client himself will weld and solder it, he will most likely buy some kind of ready-made box.
Our client "vipos" has a similar thing, they also have a vending machine in their salon and you can pay with a key fob there.
From the OneBox side, here you need to integrate with the device's API. I don’t know how technically developed the vending business is and whether it provides at least some APIs. 50/50.

To really help the client with his questions, or find out which particular device from which manufacturer he wants to buy (and we will contact you, find out about the API and contactless payment),
or directly connect the client here, let him tell the details (if he knows).

The point is that the client himself will make these vending machines.
And he needs to understand what hardware and software module to install to receive payments and so that later all the data gets into a single system

The point is that the client himself will make these vending machines.
And he needs to understand what hardware and software module to install to receive payments and so that later all the data gets into a single system

In order to give a specific answer, the description of the request contains few details, both in terms of what functions the machine will have, and in terms of the level of security that it must provide.
Generally speaking, this task can be solved by installing any embedded computer with low-level interfaces (for example, Raspberry Pi or its analogues) into the machine and connecting any of the NFC or RFID modules available on the market (it all depends on the budget and the required level of security). ), plus the control modules of the venous automaton itself. Having an embedded computer, it becomes possible to implement a set of simple scripts in any programming language that will interact with OneBox using an already existing API.

Maxim, did not try to look?