I have a calliper.
Do you like to know the thickness of the cherry 5000 or of the 3000.
The keys in the middle of the 5000 could be removed easily.
For the 3000 I would enjoy some further hints, to avoid any damage.
The easiest way is just popping the case open and then pulling Esc or somesuch.
In order to open the case, you unhook the latches at the top of the back (easily done by hand), pull away the upper case part, reach inside to make sure the circuit board comes loose from the upper part (push it in), and then just wiggle carefully until the top case comes off entirely.
Getting it back together is a bit harder but mainly involves a bit of patience, since all the parts have to fit well. First the top case needs to be hooked in at the front, if done correctly it will go down easily. Mind the cable, hook the PCB back in, and for the latches best work your way from right to left.
The 3000 is more interesting since it is from sort of a transitional period. I already have measurements for 1996, 1993 and 1989 boards.
A special tool I do not own.
Do you think two loops of wire are appropriate?
That should be plenty. An IC removal tool also seems to work well (they should stock these in well-sorted stores for electronic components).
EDIT: OK, so that would date the thinner keycaps to late 2001. Maybe
all the Czech-made boards have them?
Incidentally, I think the only more or less direct upgrade from a Siemens board would be the $pendy option - Topre.