Need USB3 stick with metal casing and at least 40MB/s sequential write, 80MB/s read

That looks very good, Kimputer. That model seems to be available only in 128 GB - quite expensive. We'd be happy with 16 GBs already, that's why I tend to buy and test this one: https://www.sandisk.de/home/usb-flash/ultra-flair
Thanks

Please note how Sandisk is smart about labeling higher and lower end USB. The higher end (Extreme etc) will have a write speed stamp, because it's really tested and rated at those speeds.
Lower ends, will only notify you of the READ speeds, leaving the write speeds a bit "open".
When writing speeds are not specified, the reading speeds should NOT BE an indication (some have VERY high reading speeds, but are still stuck with 10MB/s writing)
In your case, the Write is speed is not indicated, and you have to "guess" how much the real sustained write speeds are.
Having tested the write speeds of several Sandisk, when the write speeds are mentioned, you don't have to doubt those speeds (which is basically the reason why they make it so obvious)

Another admin recommended the ultra flair one and tested at roughly 40MB/s writing which was our limit, so it should be ok. Surely, the extreme is so much better.

Yes, then you have your answer already (since Sandisk doesn't change USB internals that often, so the 40MB/s should valid for a while)

Why does it need a metal case to be engraved, you can buy wooden cases to glue your own choice of USB stick into and engrave that instead. What quantity are you looking for?

Hi andyalder.

Quantity: 75. What wooden case wold you use for example for a corsair voyager slider x2? It should not look clumsy. We are looking for a slim stick, one that wouldn't block the other usb port beside it.

Wood won't be as slim as metal but you can't judge from the external size of your Corsair Voyager until you strip the plastic case off, I presume the makers of the wooden-cased ones can buy uncased sticks but if you need a specific stick inside then you would have to check with the makers. Might be worth having a word with your local photographer as they use them for weddings.
I would phone http://www.flashbay.co.uk/usb-sticks/nature  and ask them but only because they're assembled locally.

Flashbay does not sell fast sticks, I had phoned them some days ago and was told: "at the moment, we work with models that will do 10MB/s writing sequentially, even for USB3". But no, let's leave the wood thought. There are metal ones that are fast enough, and I don't think we can get slim wooden-encasings that our people would like. They are looking for metal.

could you not use plastic ones - they can be engraved also?

Hi. No, metal is a requirement (corporate identity).

Good and precise suggestion. Unfortunately a bit too costly. I'll continue searching after my vacation and share the results. Close this for now. Thank you!