First of all underrail is a great game, got it and love it. The crafting is good (could be better) but it has a big problem - it's hard to find needed items to craft. It gets much worse with long REAL time stock reset for merchants. Specially at the start, when you don't have too much traders, so some builds are screwed for HOURS of real time, before you can get/craft needed items (like sniper rifle)
I suggest 2 things, that can make gameplay much smoother:
1)Option to "order" items from merchants based on your mercantile skill. It can be double price,but the quality of item will be identical to mercantile level (or what's best for ballance)
You can order only 1 item per merchant and you will have to wait restock to order again (so no spamming/getting everything)
Item type have to match merchant's speciality (weapon dealer will provide gun parts etc)
With this you are not spending hours waiting, running/reloading to check every trader for the last needed part, or cursing bad RNG/luck
2)Put a countdown clock in merchant's menu to see, when it will reset. I had so many infuriating moments, when I didn't had enough money, or skill - went fast to level up/get some quest - return to see all reset to a new stock with needed items gone.
The gameplay is great, but after restarting many times (new ideas for build/screw some builds/etc) I got many times this invisible wall of "can't progress properly with this build, cause I can't craft @@@ item" And the point of this game is to make a specialist, which is crippled until RNG bless you with needed parts. A sniper build without sniper rifle, or heavy melee build without metal armor, etc.