Going into the puzzle, I wanted to get to rate 9, but as a relatively new player I think this is the best I could do in in the time I had. I think theory min is 9? Well, maybe a fraction less (like 8.4?) if you use 4 gold to make 5 products, but good luck with that. Regardless, the solution you see here is extremely close to being rate 10; every arm has a wasted cycle at the end except the one holding the metal. It could return the waste metal a tick earlier but there is an earth atom blocking the conduit, and no arm can reasonably get it out of the way. Arm 8 could, but it's too busy pivoting the intermediate product and no other arm can do that. There is not really enough space for an additional arm anywhere either, so I think that getting lower than 11 would require a total redesign.

When I realised that (not before messing around for a few hours hoping to find the 10), I shaved 90 gold from the right chamber since I no longer needed the infrastructure to drop an atom in the conduit every 3 ticks. Didn't really try to optimise for cost beyond that, but maybe what I did is enough to gain a few spots.

Well, hopefully min +2 is enough to land me into the showcase stream.