I print them four at a time but there is no time savings in doing multiples. The print time for four (one chair) is six hours. Total print time for all 36 pieces was 54 hours.
The material used is called TPU which is Thermal Plastic Urethane, a rubber material. Very tough and durable once it has been printed. Very good for this use.
I made a TPU (RED) case for my Apple SE cell phone. This too was a great application. I earlier posted some other red TPU prints in this blog. I now have to look for other uses for the TPU material.
Now that I have mastered the process for printing TPU, more projects with TPU will soon be underway.