The best towers are lifts. Mobile ones that can hold one or two machines. If you ask around or post a sign in your club you may have contractors who will provide or loan you a lift for a tower. With the mobile lift, you can throw a tower type bird today, a higher one tomorrow or throw it from another location all together next shoot. The biggest plus with the lift is that you don't have to hoist or carry targets to the top. Simply lower the lift and load the machines. Much less chance of someone getting hurt. You do have to have someone who knows the machine and how to rig it for weather etc.
As mentioned above its better to buy a portable tower.
Most sporting clay shooters have the attention span of a gnat. Once they see a target a few times, they want something different. Having a single stationary tower will be GREAT the first year but in time it is used less and less.
If the facility changes... then many times that old tower is just stuck there unused, gathering spiderwebs.
I own a range and have talked to umpteen ranger owners many times over about this subject. Obtain a portable tower/manlift/scissor lift and you will be MUCH happier in the long run. With the current high prices for steel, a stationary tower (that is stable/functional) is NOT a cheap endeavor as maybe it was in the past. Definitely not at a price where you would want to see it go unused.
My neighbor is making me one out of steel 65 ft.with a elevator to raise and lower trap to load it with a winch ran off of a gas generator using 2 guide wires for the wind to stabalize it,Making it this winter,he likes projects like this,Dan
Elm Fork in Texas has a huge tower that can throw a target almost anywhere on the property. It is neat. Even though we have the attention span of gnats, the sporties shooters see lots of targets off it that they learn to hit. I have seen a tower in Wausau Wi that was built with the posts from a billboard. Most of the fixed towers have rigging that allows a trap to be lowered to the ground and reloaded. If you shot the FITASC Worlds at Northbrook you saw some 90 foot portable towers that made for some wild targets. I believe these were rented. Look in the back of the sporting clays magazine and there are people there who advertise towers and traps. if you plan on buying a ten or fifteen footer, don't waste the money. You can move a trap back a few yards crank up the spring and get the same effect. Try to look at the new bases from Casey Rennert, as they allow you to do a lot with target presentations.
If you want to learn tower shots, you will have to practice them.