Day 307 - Penny Traps: A good first print for the classroom

This is the sixth in a series of posts about getting started from scratch with 3D printing. Our posts so far have focused on the mechanics of printing a simple model with various types of settings on the MakerBot Replicator Mini:

• Day 302 - Unboxing and setting up up the printer
• Day 303 - Rotating, scaling, previewing, and printing a simple octopus model
• Day 304 - Adjusting layer height and infill to save time and money
• Day 305 - Creating a custom slicing profile to adjust raft and floor
• Day 306 - Using scaling and custom slicing to remix a model for a new purpose

Today we'll print a model that is particularly good for a first-day print in a 3D-printing class: a Penny Trap. Halfway through printing you Pause the printer and insert a penny into the model. Students love doing this, and it's a fun model for them to take home and show off to their friends and family after class.

Thingiverse link: http://www.thingiverse.com/thing:405528

The Penny Trap a great example of the difference between the additive nature of 3D printing (where a form is built up from nothing) and the subtractive nature of other manufacturing methods (where forms are cut out of existing blocks of material). With subtractive manufacturing it would not be possible to construct this model, because the penny cannot be inserted through the holes. However, with additive manufacturing we can add the penny during the print, forever trapping it inside!

Going further: If you want to make traps for different coins, you can find models sized for many major currencies, or even customize your own, with the Customizable Coin Trap model on Thingiverse.

Thingiverse link: http://www.thingiverse.com/thing:193941

In our GSCI 104 Introduction to 3D-printing courses at James Madison University in the 3-SPACE classroom, everyone prints a Quarter Trap on the first day. They love it:

Pro tip: Coins, especially pennies, can get really dirty. To clean up your coins, soak them in vinegar for a little while.