Is he crafting for survival/exploration/gathering game? That's seriously the only place I've seen those made.
Crafting Time
One day of one month...What are you making this time?An altimeter!An alti-...huh...?
It generally varies by 1 hectopascal per 8 meters.
I thought it'd be fun for my drive to the con in Kyoto.How does it know how high up you are?Air pressure and temperature change depending on elevation, so it measures those!!Wowww, amaaazing.