The DMM body comes with a segmented LCD that's connected by a zebra strip.
The battery compartment connects to the PCB via spring contacts.
The buttons are carbon covered rubber stamps, which are shorting the exposed pads on the PCB.
Example Project:
As I am from the lighting industry, it has always bothered me that I had to power things up in order to measure the forward voltage of the LED string. For DC systems, most LED strings
or COB-LED's (ChipOnBoard) are 6 or 12 LED's (18V / 36V) - but you never know.
The diode functionality of DMM's often doesn't even go up to 3V.