Quite a significant exploit here:
You can make 25 arrows for 4 junk matter, then convert those same 25 arrows into 5 basic matter, those 5 basic matter can then be converted into 5 stacks of 999 junk matter, repeat, infinite junk/basic/advanced matter.
Also, you mentioned in an earlier post that advanced matter requires the alchemical forge (or it will eventually), I can still make it standing near the alchemical workbench/anvil/loom from 10 basic matter and completely skip everything up to the Wall of Flesh.
There are a number of pricing issues, one that comes to mind is the meteorite bars being 60 advanced matter while the meteorite set is 120/140/160 or something significantly less than the amount of bars the set actually requires. Pretty sure there's even more than that, but I just exited the game and I'm lazy right now.
Last issue I see is the crafting menu itself... Absolutely cluttered with a mess of stuff. The only way I could imagine fixing it is by using a UI with each station, reducing what all can be crafted (such as, instead of allowing direct crafting of all wood furniture, make it so you can only create the wood blocks and those need to be crafted into furniture as normal, but that means there is no breaking it down again), splitting the matters into more types (junk matter for all bricks/dirt/basic blocks/basic walls, bio matter for all plant/wood related materials, mineral dust/matter for all ores/gems/crystals/glass, advanced matter for weapons/armors/accessories) and limiting those types of matter to what they are (no converting junk matter to bio or vice versa for any types). The UI could also have multiple slots to place other items in it to limit crafting to a 'tier' unless specific items are provided to unlock tiers up to that item, maybe those items could include:
- Coral from the ocean (ocean-related stuff)
- Spores from the jungle (jungle-related plant stuff, weapons/armor/accessories included)
- Sunplate block from sky islands (for weapons and accessories found only on sky islands)
- Hellstone from the underworld (for underworld-related stuff)
- The crystal ball from the wizard (hardmode stuff)
- Crystal shards from the hallow (hardmode as well, hallow related maybe?)
- Ichor/cursed flame from the crimson/corruption (hardmode, crimson/corruption related)
- Various mob/boss drops
- Whatever else you can think of
All of that could limit how quickly someone could progress/skip things. How would that be done? I don't know. Could it work/look good? I believe so. I only wanted to inform you of an exploit and issues I have come across, as well as offer a suggestion.