The ones available at the pet stores have several disadvantages: They are usually too short, have too small diameters and an annoying platform which doesn't allow 'full speed' upward.
This design allows you to make a scratching post from floor to ceiling, in whatever length your cat prefer, and it's also very stable and doesn't require any holes or screws to fasten. It is also possible to re-wrap the Sisal rope in the future.
The relaxing platform and staircase described at the last step are optional.
Step 1: What you need.
* Sisal rope, diam. 8 mm, approx. 47 meter for each meter of the pipe length.
For example: A diam. 110 pipe with length 2.5 m will need 117.5 m.
Sisal rope can be quite expensive, so check out where you can buy it cheap.
An affordable supplier is http://www.ropesandtwines.com (delivers worldwide).
(See below in comments section for the formula used for exact calculation).
* Tee nuts, M8, 4 pcs.
* Hexagon head bolts, M8, length approx 50 mm. , 4 pcs.
* U-bolts, 2 pcs.
* Fake MDF wood tiles. (Or a similar hard surface material).
* Cork gasket sheet, thickness 3 mm.
* Wood screws.
* Ordinary hand tools.
* And the most important: One helpful and curious cat