I have thought about sending stuff down to magma furnaces before, but id just have to haul it back up wouldnt i? or is it possible to set up a cart system back up (this time carting stuff up 50z levels).
You can do that. My current setup has a 3x3 spiral tracked ramp, near a staircase, and a ... about 100z drop chute. At the top, I have a 1x1 stockpile/refuse zone, which I use to hold all my dumped ore & goblin-donated metal goods. A 2x track picks up ores & metal items, guides it over and dumps it into the chute - the bottom of which is next to my magma smelters. At the bottom of the spiral ramp, I have a large stockpile which takes my crafted goods & bars from the smelters & forges. The bars are gathered from the large bottom stockpile, and quantum piled into a stack next to the forges with a small track. The bottom spiral track stop takes goods from the big stockpile, and hauls it up top, where it is dumped into another 1x1 stockpile, where it can be moved wherever.
The main problem with this setup, because I have one housing area, is that haulers have to run all the way down the stairs to move goods or push carts. And that metal masks do not fit into any category, so they are never put into the minecart to be dumped to the smelters.
As I actually start mining (if I bother), I'll branch off from the stairs, and connect new track stops to the spiral ramp. Feeder stockpiles on various levels will pick up ore, and haul them to the top of the ramp, or maybe just dumped straight into the chute. I've been getting so much metal from sieges that I haven't really bothered with that yet, plus the large amount of gold & silver from digging out the fortress.