I created this soldering jig to assist in the assembly of the Automatic Pill dispenser project from @shaztech.

Here's a link to that really cool project

https://makerworld.com/en/models/389626#profileId-290681

This helps you get the headers precisely aligned and consistently spaced so that multiple trays line up perfectly, and the boards line up with the screw holes in the tray. This can be done by working the boards in pairs with the male and female headers plugged into each other. It also has a space to align the header to the main board. (See photos).

I printer this in PETG and had no trouble with the heat from soldering warping the model. PLA may work as well since the heat is all on the top of the circuit boards.

The model is made intentionally for the boards to fit very tight and are held in place with friction. When you are done, you can flex the jig, and the boards will fall out.

I created this based on the boards I received. They are exactly 45mm wide. If yours are different, you may want to adjust the model. I included the STL file so you can do so.

Let me know if anyone has questions.

Hope this helps.