How to make a perch?

Hi,

I remember reading a post some weeks ago about how to construct a suitable perch. Simple things like dimensions of the wood, etc.

And I remember it said the edges shouldn't be roundy because it can damage their feet.

Can't find the post at all now and I've been reading other posts about perches where people are saying they have rounded off the edges.

Can someone tell me again what dimensions of timber make a good perch, should it be left square or rounded off and how high does it need to be off the floor?

I had in mind to make a kind of removable 'rack' arrangement which would sit about 8" or 9" off the floor and with 3 or 4 beams which would be the 'perches'..... although they would have no choice really and wouldn't be able to walk on the floor at all.

Is this no good?

Thanks

2x2 or 3x2" is good, if the perch is too thin the birds toes curl underneath and are not kept warm in sub-zero temperatures.

We use 2x2 with rounded edges at the top.  Or 3x2 if they need to span a longer distance like these