What is the perfect cage size?

Im building a new cage, probally rectangular and i need a good size for an adult ball python. What would you guys recomend? Also any tips on building a cage would be much appreciated.

Have U checked out the caresheet yet? Balls like being scrunched, so you won't want a lot of height, just long enough for his adult length to stretch out and enough width for the hides w/a little more. Around here it's about 5'x2'x2'.

The sterilite 1960 tub should be a good size for an adult, believe they measure 33 x 17 x 6 or something like that. Might wanna check out the caging forum for tips and links on do it yourself guides.

From everything I've been told, a 20L tank should be good for the whole life of your snake. They're usually 30x12x12.