There are plenty of the way to make what you offer rarer without becoming obscure. At this level, the common mining drones are the ones you should have a look at (each tech 1 and tech 2 versions). https://xn--L3Ca4b8epb5B.com/category/%E0%B8%84%E0%B8%A5%E0%B8%B4%E0%B8%9B%E0%B8%AB%E0%B8%A5%E0%B8%B8%E0%B8%94%E0%B8%A1%E0%B8%B2%E0%B9%83%E0%B8%AB%E0%B8%A1%E0%B9%88/