Build a Matlab function

I need a function in Matlab that takes in input a STEP o STL file and 3 sizes (x,y,z), adds to the 3D model (loaded from the STEP/STL file) elementary volumes (cylinders and rectangular boxes) in order to create a bigger box with sizes x,y,z.
It returns in output added volumes (type, sizes and location).
Other programming laguages can be evaluated.