This page is where I'll drop ideas that I come up with for developing collaborative lessons for 3D Printing in my classes.
Idea #1 - Design around a seeded object Give the kids an object that is their starting point. In my case I've done this a few times. I seeded my kids with 110mm tubes for use with the Marble Run project. I also seeded my kids with wheels for the Great 3D Printed Car Race. This allows kids to build around specified parameters. They can simple use the measurements or they can import the objects into TinkerCAD and incorporate them into their designs.
Idea #2 - Team design of elements Divide the kids up into teams or pairs. Start with a grand idea or final project. Define the parameters ahead of time, either as the teacher, or collaboratively as a group. (take into account grade level and ability) For example: The final product is going to be a dollhouse. One group would be responsible for the roof, another for the shell, another for the doors...windows...etc. Measurements would be defined and the kids learn to work within those parameters. There is a lot of learning that takes place when the kids see how their project will fit together. There are many projects that you can do this with. Another idea for younger students...design train cars to be part of a larger train...etc
Idea #3 - Using Peers for Quality Control This is a simple concept where you allow for students to share their work, either digitally or in person, for a second set of eyes to review. Use this as an opportunity to teach kids what to look for and share common points of failure in 3D modeling. (things like embedding, structural integrity, etc) This also allows you to teach engineering concepts like structural integrity...etc.
USE Google Classroom - Google Classroom really makes it easy to submit and work with digital models for 3D printing. Whether you are "self-printing" (allowing the students to print) or having the students submit their models so you, the teacher, can print them...Google Classroom really makes this easy. My students always export their models in TinkerCAD as .STL files. Then in Google Classroom, they go to the assignment for the current 3D printing project and click "Add" > "File". This gives me access to the model for viewing and critique as well as the ability to download the models individually or "en masse" for printing.