Size of stl files

I have two .3dm files of two separate models, with two matching .stl files.

The first file is of a bracelet. The size of the .3dm file is 6.6 mm, the matching .stl file is 2.8 MB

The second file is of a brooch. The brooch is much smaller in size than the bracelet. The size of the .3dm file is 2 MB, and the matching .stl file is 36.7 MB.

The designs of the bracelet and brooch are similar in that they both employ only round wires of identical 1.5 mm diameter.

Why is the second .stl file so large?

I have a second .3dm file of a brooch of identical design as the first one, with as only difference that the wires have a diameter of 1.25 mm. In this second brooch file with 1.25 mm wires I was not able to do a boolean union of all the parts even though I was able to do that in the other one with the 1.5 mm wires.

Hi Zews - see if the info here

helps at all.