This seems really unfinished... Let me see.. Netherrack is something you can get with a wooden pick by the hundreds. Blaze rods are incredibly hard to come across and you get them from creatures literally made of fire... And they can only cook one item? I understand that with Netherack but blaze rods? Definitley not... Blaze powder is also a really crucial material in making eye of enders, and if they are used for fuel they should do a hell of a lot more, you wouldn't want to waste rare resources! VInes seem reasonably... But sugar cane is needed for a lot of things, and has a much larger mass then vines, and probably wouldn't burn well anyway... String is also really hard to come buy, a stack would take hours to get, and just for four items? It would be faster to go punch a tree and smelt a stack of iron then to smelt four using that... Paper is made from 3 sugar cane, so it should be a lot but paper isn't really that big so that is rather accurate... Wool is another rare material a bit, but it does burn quickly so that is accurate, dead shrubs and tall grass are perfect, and cactus could be a bit more but .5 seems reasonable... And seeds seem OK. I like this idea, but it needs some refining... Hope it turns out well!
netherrack=1 Nah. Way too common in the Nether anyway.
blaze powder= .3 Meh. Kinda ruins it for the Blaze Rods.
blaze rod= 1 Blaze Rods can already be used as fuel...
vines=.5 Uhh..??
sugar cane=.1 I don't think so...
string=.0625 (so a stack of 64 would cook 4 items) That's pretty useless. And a waste of string, given the other fuel sources.
paper=.2 Meh. Too small/useless.
wool=.5 Hmm, plausible.
dead shrub=.0624 Useless.
tall grass=.0624 Useless.
cactus=.5 Awkward to make cacti a fuel source when they themselves can be smelted.
seeds=.1 Useless, but still a bit plausible given how easy it is to find seeds. Though I can't imagine seeds being a viable thing to burn as fuel...
all the blocks or items are for just one, and the number is how many items it cooks
netherrack=1
blaze powder= .3
blaze rod= 1
vines=.5
sugar cane=.1
string=.0625 (so a stack of 64 would cook 4 items)
paper=.2
wool=.5
dead shrub=.0624
tall grass=.0624
cactus=.5
seeds=.1
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Almost every single one of the items you listed on the list is needed for more important things. It shouldn't be flammable.
Dead shrubs aren't obtainable, I don't think.