Yes, I was successful in building exactly what you are describing. It cost me about $500 or so. These are masks that move up and down as I my projector uses constant width.
The system uses modified DrapeBoss X10 motor drives, one for the top mask and one for the bottom mask. The DrapeBoss motors have up to 8 programmable stops, so they are perfect for use to give you 8 different aspect ratios. Aspect ratios are randomly accessable at the push of a button.
I basically modifed the motors to the extend that I built brackets that let me take the case apart and mount them so that the drive shaft couples direct to the end of a roller. It's much like a wide roller type window shade, except that I used black velvet for the fabric. Where you would normally have a slat to grab to pull a shade down, I inserted a piece of Aspen 1x4 lumber. Aspen is light and you can find straight pieces at Home Depot.
Motors are avialable from Smarthome.com for about $200 each (it takes two).
Minimal wood working skill to make a bracket.
Some sort of straight round roller about 1 3/4" or so thick.
Some way to sew the black velvet to make a rod pocket.
Access to a serger (type of sewing machine) to bind the edges of the velvet
I used a hollow metal rod that isn't available or I would recommend it. You'll have to figure out something. You would staple the velvet to a wood pole, I drilled holes and used tiny metal screws every 4"-6" to hold the velvet on my metal rod.
Obviously you can't roll the bottom shade uphill. I ran a nylon cord from each end of the shade pull (1x4) up to a small pulley, across a few inches to another pulley and down to a sandbag. These have just enough sand so that the shade remains tight and smooth. One on each side.
There are two other sandbags in use. The DrapeBoss has a built in slip clutch. I found that over time these would creep, so I decided to nuetralize the twist on the rollers so the motor saw no weight whatsoever. Simply wrap a nylon cord around the roller in the opposite direction of the pull of the velvet mask and add enough sand to counter it's weight. Now there is no pull on the motors at all.
This sounds terrible, it works perfect without problems of any kind. I got the sand bag idea thinking about what they use to counter balance scenery weight for stage work. Worked perfect and easy to adjust weight.
I made what I call "view shields" for each side of the screen to provide a sharp black edge that matched the masks as well as cover the rollers, motors, weights etc. that are located to the side of the screen. These are simply frames made from 1"X 2" Aspen lumber with black velvet stretched over them. Not only are they on the side, but top and bottom also. This way, the rollers are also hidden. All you see from the viewing position is solid black.
I am building a web site for the purpose of presentning this system to interested members. It will have photos, diagrams, etc. It's just not done yet.
Meantime, for anyone who is actually going to get serious immediately with such an installation for their front projection system, I will email some temporary photos that will help a great deal. I'll also answer email questions. I don't want to get into emailing them to just the curious becuase of the workload of doing so. The curious should wait for the web site to be finished which will be very thorough. I am also hopeful that others who build such a system and come up with new and better ideas will share them with me so I can add them to the site.
I would post several photos to this thread, but I am afraid they are too large and I don't want to do so without Alan's permission.