Saying all that I've a need for more metal! I'm in the market for a copper and a bronze but equally I needed to do it on a budget. Most of the art acrylics go up in price to GW equivalent as soon as you say the word 'metallic'. You do get about 3 times the amount of paint though so it isn't that bad. They have an awesome copper and bronze but I thought I'd go for Tin Bitz, just because. I'd been doing a pretty good approximation by mixing Mechrite Red and Chainmail but that's not sustainable when I need the red for basing.
With the Drop Pod in progress I decided the interior needed more variety than Chainmail and Gold. I'd also tried the Gold on the back of my Dreadnought with shocking results and needed a way to rescue this. In the mean time I'd seen this story on GW's website. Michal Gmitrasiuk had painted some awesome Blood Angels and I wondered if I could use the same battered gold/bronze effect on my Drop Pod...
So with Tin Bitz in hand I wondered what I could do? A simple dilution with water and as a wash it's awesome. Suddenly everything looks like it's coated with a stained oil. I'm not sure how well it shows up in this shot of my DropPod ramp but it's a nice effect that could be enhanced with more washes. As a dilution of paint you'll certainly get more coverage than using a wash to get the same effect though so it's a neat little option.
Additionally it made a perfect base on the 5 uprights of the drop pod. Then a 50/50 mix with gold and there was a pretty decent bronze that when stippled in place was starting to approximate Michal's effect. With a rough 30/30/30/10 of Tin Bitz, gold, chainmail and silver the next set of stippling was even more effective. The end result isn't quite as good as Michal's [but then have you seen is painting?!] but his tutorial on CoolMiniOrNot [that I found after this] has a few more process involved and a lot more washes [which I wasn't about to shill out for].
Overall I really rate Tin Bitz as a versatile paint choice that can really broaden the options of what you can do with just a pot of chainmail and gold.