Advice needed!

Hello, guys!
I've just realised that one friend of mine knows how to work with wood - he actually has his own shop, and he promiced he'll make me a gym/scratching tree for my Solomon. I just need to explane him what I really want.... So, since I've never owned one, I have decided to ask you- what should I look for? I mena, I looked at the tonns dif pictures, but still not sure what to be aware of- like carpet, form, and other staff....
Thanks in advance for help!

I personally think it's important that the tree is as high as possible, because a lot of cats like to stretch out to their full "height" when sharpening their claws. Many scratching posts just aren't high enough. Stability is obviously significant, and having washable cloth parts is quite convenient, too. Our cat likes to nap up in his tree, so maybe a platform/tray with low sides with a comfy cushion would be a nice feature.

My cats like to sleep in the highest perch of the tree. They sometimes fight to be the one on the top level. I would suggest that he make a couple of platforms the same height at the top.
Sisel rope is good for scratching
A paratially enclosed area is a good idea to have so the cats can get inside and nap with privacy.
The closer you can match the carpet color to the color of your cat the better! They tend to leave alot of cat hair on the carpet

That is very very cool!!! We're also making some additional trees, and shelf beds for ours.

Some good replies already, so I'll just add to make sure that it has a very large sturdy base so it won't tip over or wobble when the kitties are scratching. Also my cats love sisal rope, and it will be easy to take off and replace on the posts.

Huge thank you, guys!
I'll keep you update how's everyting going with that and then post some pictures! For right now I made a "kitten gym" myself from boxes, threads, toys, paper... My baby likes it- look under "pictures thread"- for pictures!
Thanx for great advices!