This is textbook bubble reasoning. Nowhere did you assert why the comparibles you cited are justified in their sky high valuations. Not to mention that all the companies you cited aren't even comparibles because they are 3d printing manufacturers. Yes, you can make money in a bubble as the price rises, but eventually the bubble will burst
Renishaw looks interesting indeed. Just read through their annual report. Solid numbers and - in my opinion - bright prospects regarding their additive manufacturing business with the integration of German LBC GmbH. Bought a few shares this morning. Can't believe I didn't have them on the radar so far.