Is there anything more I can do besides roasting the coffee beans?
I'm not sure you can even roast them - at least probably not properly. Roasting coffee requires precise temperature control which is incredibly hard to achieve with a popcorn machine, an oven or a pan.
I would like to show I put effort into them and give them a unique taste.
After picking the coffee cherry you cannot really add any quality or characteristics to the bean. The whole process can be seen as a series of windows - if everything is done well, you can see the coffee and its origin characteristics. If something is not done well, the window gets stained and the view on the coffee gets muddy. The main thing you add with roasting is sweetness, notes that go into the chocolatey and nutty area and bitter/burnt aromas.
I have plenty time and coffee for trial and error.
If you really do want to roast them yourself despite not having the ideal tools for it there are several things to keep in mind:
- Make sure all of the beans are roasted evenly. This means keeping them moving a lot and not letting some beans be in contact with the heat source for too long.
- Do not roast them beyond the second crack if your father does not like overly bitter coffee.
- You're dealing with temperatures of above 200°C, take appropriate precautions.
- Remove any defects like chipped beans or quakers afterwards so they don't negatively impact the taste.