[TriLUG] Linux - Which CAD program(s)?

[C TC via TriLUG]

Hi all,

I have a couple of STL files from thingiverse that I'd like to modify.
Would appreciate some software suggestions for those in the know.
Will be using either my Mint or CentOS systems. Of course, I can use
a VM of any flavor, should someone suggest it. Planning to send
out for 3D printing.

Thanks,

~Carl