Cat Tree DIY– How to attach pipe to the base?

Cats love to climb trees - and get stuck there, of course. A homemade cat tree will provide your kitty with hours of entertainment and fun, also, homemade cat tree will save you lots of money . To DIY a cat tree, you'll need to create a tall structure with a few different levels where your cat can perch.There comes an problem , how to attach pipe to the base ?