dont worry the cart can be achived with ease - start by getting smaller amounts of copper and tin. process them into ingots - process the ingots into bronze and then make some nails

this is all i can write down without spoiling too much
nails are key for the next tier of transportation
but dont pack the cart full of ores - you yould not be able to move it but i can pack a couple of stacks and make things a bit more easy