you are able to make a stamp of one pixel with S key, then load the stamp with L (last stamp) or K (list of stamps). use ctrl + arrow keys while the stamp is loaded to align the pixel then
use the wiki https://powdertoy.co.uk/Wiki/W/Hotkeys.html
you should post questions to the help section, not creations next time :)
you can only have a max of 5 pixels in one pixel before it colapses into BHOL, also i just use the arrow keys by themselves ;3
TOOOOTALLY not using elecrtical magic to rewrite the system using ultimate flaming star powers
Your comment was just a bit too late. But srsly, last reply was 4 years ago. Please don't reply on threads that are ancient. Thank you.