Hi, I designed an adjustable motor holder for 12V DC motors just as this one:
https://www.amazon.de/Greartisan-Getriebemotor-Mikrodrehzahl-Exzentrische-Ausgangswelle/dp/B071XCX1LH/ref=sr_1_15?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=1LYXRIGYATT2W&keywords=getriebemotor%2B12v%2B50rpm&qid=1697469322&sprefix=getriebemotor%2B12v%2B50%2Brpm%2Caps%2C93&sr=8-15&th=1

Things you will need for assembly:

4x M3 Screw and nuts to hold the motor to the holder plate

4x M4 Screw and nuts to hold the plate to the holder to be able to adjust the height

4x M4 Washer for mounting the plate to the holder

4 Screws to mount it at whatever you want :)

If you need a smaller version look at my profile :)

Print profile coming soon.