With digital projectors as cheap as they are today, it's a shame that screens are still so expensive. Many screens out there cost more than budget projectors do. However, you can get a decent screen from numerous online vendors for a few hundred dollars. (The larger fixed screens with fancy screen fabrics and nice masking systems you'd like to have can cost several thousand dollars.)
Given my experiences with samples of the hyped-up screen fabrics out there, my preference is definitely to use blackout fabric and my own frame for a total cost of about $50. Frame it and stretch it
Building a basic screen isn't much more difficult than building speaker stands. That might seem hard to believe, but a screen is just wood and fabric. If you can build a simple wooden frame and follow some simple canvas-stretching techniques, it'll be a piece of cake.
Begin by getting some 1/4-inch flooring plywood. Cut the plywood to your desired screen size (note that this technique limits you to a 48-inch-tall screen). You'll also need some 3/4-inch pine shelving material that you should cut into strips 3 to 4 inches wide, sized to make a frame that will mount on the plywood.
I chose to construct the frame using simple but very strong fishplate joints. Figure 3 shows 1/4-inch cuts into the pine on each side, with a piece of plywood for connecting the two edges.
Figure 3. Fishplate joint with pine and plywood
Once you've glued the joint, use a staple gun to sturdy things up (see figure 4). Now, you can mount this entire frame on your plywood, as seen in figure 5. The plywood makes this frame very rigid and provides numerous options for hanging the screen. I've had success cutting a couple of small square handholds in the plywood. This makes the screen easier to handle and provides a perfect fit for 1/4-inch mirror hooks. I'll leave it up to you to determine the best way to mount the mirror hooks to your wall, or you can come up with another method that works for you.
Figure 4. Completed joint
Before you start stretching the fabric, I recommend sanding down the outside edges of your frame to round them off. This reduces the chance of ripping the fabric as you stretch it over the frame. If you have a router, I also recommend rounding off the inner edge of the frame to prevent it from pressing against the fabric. If you don't have a router, sanding will have to do.
Now you need to add the fabric. Plain white blackout fabric will work, and you can get this at any fabric store. If the salesperson doesn't know what you are talking about, ask for the fabric that backs curtains to prevent light from passing through. Lay out the fabric on a flat surface, cloth side down, and place the frame on top; make sure you have at least one inch of excess fabric on all four sides of the frame, and if you have significantly more than that, cut it off. Also, smooth out any wrinkles.
Fold one side over the frame and tack the fabric to the frame in the center of the side you're working on. Do not add any other tacks at this point. Now stand the frame up so that the tacked side is on the bottom (against the floor). You should be able to stretch the fabric opposite the tack over the frame, until there is a slight crease in the fabric. This tells you things are just tight enough. Tack in the fabric.
Many will suggest using a staple gun at this point. I prefer using a few tacks, then coming back with the staple gun; if I tack something wrongly, it's a lot easier to pull a tack out of fabric than a staple.
Figure 5. Frame with borders and bracing
Now you can move to one of the two remaining untacked sides and repeat. Then, tack in the final side; at this point, you should have a sort of diamond formed from the creases, running from one tack to the next. Now, you're ready to get out your staple gun. Start in the center of one side, slowly move out a few inches, and staple. Then repeat, in the opposite direction. So, you're always moving out in one direction, stapling, then moving out in the other direction, keeping the tension even and the creases moving toward the corners.
When you get to the corners, tuck one side under and fold over, and you're all set (see figure 6). Finish up with the stapling, and you should have a great, taut fabric, as seen in figure 7. Although a regular staple gun will work, a pneumatic staple gun will make the task much easier; besides, what better excuse for getting a new power tool could you ask for?
Figure 6. Completed screen with staples in
Figure 7. Completed screen
This is but one method for building a screen, and I've found it easy and effective. I've seen examples online of screens that ranged from simply hanging a piece of Parkland plastic on your wall to frames made out of PVC, all the way to guys with the skills to weld an aluminum frame. There's no single right solution to most problems, and that's the beauty of DIY. Copy exactly what someone else did, come up with your own unique solution, or do something in the middle. With DIY, you're the client, engineer, worker, and boss, all in one.