I should have remembered that not everyone on this forum is accustomed to English idioms.
Riding a penny farthing bicycle was a fairly adventurous business, as the saddle was on top of the large wheel and something like 5ft from the ground. Getting on was awkward, and stopping was worse (obviously with a normal bike you put one foot on the ground when you come to a stop, but you couldn't with a penny farthing!)
A couple of others:
Bookbinding
Prince Heinrich of Prussia
Apparently, it was a Hohenzollern tradition for princes to learn a trade. Heinrich learned bookbinding, and continued as an adult (he used to make his own account books)
Heinrich was also an enthusiast for steam-powered cars. Until recently I would have described this as a technological dead-end, but somebody has just built one, and broken a speed record which had stood for over 100 years.
Decorative enamel work (it involved using a blowlamp)
Princess Marie Louise
Ann