hy solid is pretty good in such cases, and alows multiple conditions / restrains, etc, that are handled pretty well
i guess this is the reason why we love solid, so to say
time and bit of practice should help you setting mates faster
i will explain for a "scissor" : think of a buterfly no kitting .. is the same as a buterfly, well , at least from my perspective
you need 2 cilinders that are almost identical, coaxial and overlapped one cilinder is rigid / static, while the othre has this conditions :
... coaxial with 1st
... on face/ frontal on the face of the other
in this moment the 2nd cilinder should rotate arround the 1st one, more exactly arround the simetry axis of the 1st cilinder
this is key now you can build whatever arround those 2 cilinders
to obtain a beautiful scissor , materialize those 2 cilinders like this :
... on one arm of the scissor, put an "extruded" cilinder
... on the 2nd arm, "extrude cut" same cilinder
now you have those 2 cilinders materialized on solid shapes > go mate