by follow i mean have the same curvature , they are not touching
I still do not understand what you are trying to do. A square has straight lines, they cannot have any curvature. Do you mean how can you replace the straight lines on the square with curved lines that match a spline? Do you mean how do you get the square to travel along the path of the spline, even though they don't touch?
hei'ya Max, Jerry will know what you need if you a make screenshot or UL a part file,
for my 2cents, a couple of ideas on linking in a sketch are att.
on the left you can change the square dim. on top- (the sigma symbol shows it is a
driven dimension), or the circle Ø
on the right there is a single spline linked to one side of a square?
you must first define all that is known or fixed
but you can drag the spline within these confines- kelef
linkedsketch.SLDPRT.zip 64.7 KB