3D printing models in the classroom takes ages. Especially if your students decide to make some complex shapes which takes long hours to complete, so you decide to leave it on overnight just to realise one layer screwed up and everything went south after that! That’s a lot of wasted time and filament. So why not simplify the resource by getting a 3D printing pen? Of course, you won’t get the quality of a 3 axis printer; but then you can freestyle in thin air!
I got 10 pens from the Myriwell Aliexpress Store (https://myriwell.aliexpress.com/store/2707019) and the model was RP-100B. This pen does come with plenty of filament. Its plugged into the wall for power (there is a wireless model now and one which prints PCL-low melting point which is faster than ABS/PLA and is biodegradable). There is a small lcd on the pen which gives the temperature reading and buttons to choose between ABS and PLA. A slider controls the flow of filament and a button to start and stop the filament flowing. At $45NZD I thought its a steal especially if you want to prototype quick and easy in a three dimensional space.
Doing a 3D print by starting on the XY axis is very interesting as it provides the opportunity to think outside the box. Let’s say you want to draw a box. So you would be drawing 6 squares and then ‘glue’ them together using the pen. The provided template of the Eiffel Tower is actually pretty good to start with. The clear plastic goes on top of the printout of the tower, and then you draw each side and then glue it together. I was tempted to do my own thing so I started doing an X wing design (Star wars). But by the time I was half way into it, I was thinking of integrating all sorts of things to make it interesting.

For example- giving students a bunch of recycled plastic like toothpaste caps, pen refills, springs, buttons, metal bits like nails, screws, nuts, and ask them to integrate it in their design. This could be a good sustainable design compared to the hours of printing a normal job. Students also need to plan and model in 2D to convert their drawings and prints to 3D, which is cool. You could also integrate electronic circuits into the design to make a fully functional prototype.

Functionality of the pen is very practical. Minimal effort to get using the pen, takes less than a minute to get the filament going. The flow of the filament is quite steady at its lowest setting, and at the highest is useful to fill big gaps. Power cord is long enough to do some work on the desk but it can be a pain sometimes with the wire hanging over your hand.
All in all, a worthy investment to have a couple in the classroom.