Sketchup is still my favorite modeling program. I run an old version locally on a wine instance. The more recent stuff is all online which is good & bad I guess. It's super intuitive & easy to use IMO. Just remember to keep white faces out & grey faces in & be sure to close up all holes in the model. Being able to easily orbit around parts & turn transparency on & off (among many other things) is just hard to live without once youv'e had it. I have a plugin to export stl files, I assume this can be done from the online version too 🤔