View difference between Paste ID: Fq3rYPvN and jAsiedMG

 local chest = "back"
 local chest_to_turtle = "east"
 local turtle_to_chest = "west"
 
 local function sum_inv(i)
   local out = {}
   for _, v in pairs(i) do
     out[v.name] = (out[v.name] or 0) + v.count
   end
   return out
 end
 
 local function clear_inv()
   for i = 1, 16 do
     peripheral.call(chest, "pullItems", turtle_to_chest, i)
   end
 end
 
 local recipe = {
   {"minecraft:sand",   "minecraft:sand",   "minecraft:sand"},
   {"minecraft:sand",   "minecraft:gravel", "minecraft:gravel"},
   {"minecraft:gravel", "minecraft:gravel", "minecraft:dye"},
 }
 local reqs = {}
 for y, row in pairs(recipe) do
   for x, item in pairs(row) do
     reqs[item] = (reqs[item] or 0) + 1
   end
 end
 
 local function satisfied(reqs, by)
   for req, qty in pairs(reqs) do
     if qty > (by[req] or 0) then return false end
   end
   return true
 end
 
 local function move(what, to)
   for slot, stack in pairs(peripheral.call(chest, "list")) do
     if stack.name == what then peripheral.call(chest, "pushItems", chest_to_turtle, slot, 1, to) return end
   end
 end
 
 while true do
   local contents = peripheral.call(chest, "list")
   local items = sum_inv(contents)
   if satisfied(reqs, items) then
     print "Requirements satisfied; crafting."
     for y, row in pairs(recipe) do
       for x, item in pairs(row) do
         local tslot = ((y - 1) * 4) + x
         move(item, tslot)
         sleep()
       end
     end
     turtle.select(1)
     turtle.craft()
     --turtle.dropDown()
     repeat turtle.place() sleep()
     until turtle.getItemCount() == 0
   else
     print "Not crafting; requirements not satisfied."
   end
   sleep(1)
 end