Some bright spark engineer at work suggested Beryllium for some high pressure windows in our oil logging tools.

The only people we could find who were prepared to machine it were in Germany and it was done in a sealed environment - the machinist had to step into an environmental suit.

When it arrived at our factory everyone who was to handle it was given face masks and gloves and told that if any dust got into a cut it would never heal. The foreman then chiped in that a few years earlier in a previous job he visited a factory where a machinist had cut his finger, the cut didnt heal, and he had his hand amputated. I have no idea whether this is true or not, but we all bottled out and promptly told them what they could do with their new wonder material.

On the other hand, it is stronger than Titanium and half the weight. When held in the hand (with gloves - and face mask) it was amazingly light.