What would be the halacha with regards to adjusting brand new crutches on Shabbos. Most modern crutches come with pins (see picture below) on either side which when pressed down can slide into the next set of holes and thereby be altered to the appropriate height.
So, within the realm of hilchos Shabbos, do we say since it was made to function like this there is no problem to do it on Shabbos as one is merely making it the right, functional height, or do we say that by adjusting is boneh (building) or is it 'makeh b'patish' (the final hammer blow) as you are making it fit for purpose and thereby turning it into a 'kli' - i.e. a bit like threading laces into new shoes (see Mishnah Berurah 317:18)
DISCLAIMER: I know this is a question for a LOR I am merely opening it up for discussion as a means to learn more about the subject matter and resulting Hilchos Shabbos.