I am mostly a solo player and I am never in a good location to run a shop that sells stuff that people need. So when I need coin, to this day, what I still do is this, with coils:
This ended up being the thing that defined fossil and essence prices as they are today, since the addition of the minter. The values in the link above are the base values before any coils are considered for the minter.
Some other “okay” items for minting would be things like Flour made from Oorum Wheat; it’s not great but considering you can just literally grow it, it’s good for people who like to do the farming. Other okay items are Ancient Tech Component and Ancient Tech Device; especially if you have a lot of these and can’t get rid of them in a shop.
Your next question is probably “but where do I get so many fossils”? To be honest, it doesn’t even have to be a lot of fossils, but good planets for fossils are Besevrona and Norkyna, and most other Toxic/Corrosive planets. The areas that are good for fossils also tend to be good for Silver Ore, which is always high in demand and at the moment sells very very decently even at request baskets (24c per ore, wow, if only I didn’t need it for myself 
)
A thought for everyone:
The thing to understand about the minter is that it sets the lowest base price something should be worth to other players. Selling an item at a value lower than what it’s worth in the minter + coils always means less potential money was made.
Like, if you want to maximise your coin gains, you should never sell an Ancient Tech Device to someone else at less than 2.8c in a hand trade, and never at less than about 3.2c in a shop stand, because of the tax loss. Sometimes people sell at less than this likely either because they don’t realise or because they just want rid of some of the items without the bother of actually using a machine and so on.
Coils are absolutely essential to make good use of a minter because every coil basically adds 5% to the listed value you see on an item.