ABS, PLA, PETG without heated-bed!

Here's a method to print ABS without a heated-bed. Check the video/video description for details.
https://youtu.be/gqgZvppQk4w

*See printing PLA on ABS successfully here: https://www.youtube.com/watch?v=ls2m7F-d42s

*See printing PETG on ABS successfully here: https://youtu.be/N0Li4lxkOfg

This STL is a torture warping test, you may or may not succeed printing it fully even with a heated bed, but luckily I succeeded as you see in the video.