Thank you gr5. I understand all your comments, I'm an electrical engineer with a MS in robotics, but new to 3D printing. This tells me that it will be a little harder than I expected. My son's school also has an Ultimaker2, so to start we have "similar" printers, but it will not save us from experimenting there too. Later on, we are planning to help other local schools with probably other printer models.
I see the interesting spool holder that you have in the floor. I went to the web in search of a 3D printer model of a spool holder and I found tons of ideas. Do you have any comments or do you know of a better option? Or, I can simply try to replicate what you did.
http://www.thingiverse.com/thing:1001312
http://www.thingiverse.com/thing:46016
About ABS, I live in northern CA, but I'm from Rio de Janeiro, Brazil. It is not hard to find children in need of a hand there and also Rio temperatures in summer can easily exceed 40C. I have seen street thermometers showing 50C plus. So this is my motivation to learn to print using ABS. I'll only try ABS when I'm comfortable with PLA, and I'm not planning to do it at schools.