What is the easiest way to make a Promethium weapon while in a dungeon so that you can bind it?

 

The cost of Promethium Ore is really high ... doesn't a 2H Sword take five of these? At what floor level

is it even plausible that you'd be able to make one?

2Hs require 4 bars - it just takes 1-2 promethium rocks and a decent ring to get them. As far as I know the floor doesn't affect the number of mining rocks you get. To maximise the number of promethium rocks you get you will want to do a large floor with a team of high level miners. If you do so it will be almost impossible to not get enough ores for a P2H.

I actually find that higher floors tend to give more high level ore, but yeah, the most important thing is to do a c5 large with at least one 90+ miner. Even with only 1 miner at 90 you're still likely to see at least the 1-3 rocks you need.

I got enough money to buy the ore going solo on a medium floor. I just killed everything and collected the money, and alched everything else. I mined all of the ore that I found, chopped every tree, and caught every fish and alched all of it. It took almost an hour, but it worked.

The resources tend to be scaled toward your levels. Thus if you want more Prom Ore, dungeon with people with high mining levels.

I once did random duo with a maxed player (except for dg of course) on a med c5. Even with my 78 mining, he found enough prom ore to make a platebody and legs from scratch o.O