What terms I can use to say the something is very easy to do, to learn, etc?

What terms I can use to say the something is very easy to do, to learn, etc?

I have thought about easy-peasy, like "this is easy-peasy to do", or "a piece of cake".

So, in general,

Assembling this furniture is _________ [to do].

Is there a fun/cool way to say that?  Some slang that is universally understood or something?  Informal, light-hearted idioms are preferred.  I don’t want technical bureaucratese like “This should require only 20 minutes of your time”, and things like “so easy that a caveman could do it” seem unnecessarily pejorative.

A walk in the park

something that is very easy to do, and usually pleasant

Easy as ABC

Extremely easy, simple, or intuitive; requiring very little skill or effort.

Easy as falling off a log

To be extremely easy, simple, or intuitive; to require very little skill or effort. After so many years as an accountant, doing taxes is as easy falling off a log for me. Boy, that test was easy as falling off of a log!

Child's Play

A very easy task. Oh please, I've been playing guitar for 20 years—that song is child's play.

The skill you have in mind has no learning curve to speak of.

I propose cinch fron Oxford Dictionary with the example usage

the program was a cinch to use

people say its "a no brainer", meaning so easy, doesn't require thinking/brains