Bloody metric measurements - great system, couldn't and wouldn't argue
against it. But.....

Consider this scenario, good people. Ducted heating furnace in the
roof was having a good go at coming through the ceiling (being a
skilled metalworker, and a RCM lurker, I knew straightaway something
was wrong..) Turned out to be crappy install job, vis
1.Vent pipe not sealed properly (so it leaked)
2.Was sitting on a sheet of particle board crap stuff so it rotted
through
3.No drip tray set up for stuff ups.

So. Decided to get a drip tray made, its a metric world, so did it all
in Metric so as to give the order for the tray to the local plumbing
supply place. Measured L by B, added 10mm each side for the folded
lip, and put the order in. Picked it up, thought "Mmmm..."

Seems I had stuffed up the decimal point in my metric calculations -
was 200mm wider than required (length was stuffed too, but that was OK
- was room up in the roof cavity) so, couldnt get the ******* up
through the access hatch into the roof. So, had to cut it down - heaps
of work...

The Moral - I cant think in Metric, cant visualise in Metric, cant
look at metric measurements and think "nah, no way - too wide/long/
narrow thick etc etc"

How you guys cope - bloody sick of doing this...

Andrew VK3BFA.