First you need to get a good pair of black pants. Ideally they should have slightly tapered legs. Make sure all the hardware (zipper and any rivets) is silver tone. Brass hardware will look totally out of place unless you use brass d-rings, etc. for everything else. If you can find a pair of black pants, not jeans, that have lots of rivets on them all the better. Lots of pockets won't hurt either.

Get some black 1-1.5 inch webbing FIG.1 shows the basic layout for your hardware. This is only a suggestion based on professionally made ones. If you're really slick, you'll attach zippers so that they access the pockets already on the pants. The zippers are easy to attach just by doing a neat stitch to hold them down. I suggest pinning them in place before you start stitching. You might even want to try the pants on and mark with a safety pin exactly where you want them.
Fig. 1

Put D rings on all the belt loops to maximize strap possibilities, also attach them along the outer side seams. One pair just below you waist, one just below you knee. Do this by putting 2 inches of webbing through the ring. Stitch in a square and then an 'X'. {FIG. 2} webbing has a tendency to unravel and this will help keep that from happening, it will also reinforce the rings. You want these to be as strong as possible! {NOTE: the rings on the above pants are actually turned the wrong way... this is so you can see their placement. The rings should be horizontal and the webbing holding them on going down the leg.}
Fig. 2
Now, you need to make your straps. Depending on your height you'll want to make them about 2-3 feet long. For every strap you'll need 3 feet 1.5 inches webbing, and 2 clasps. These can be found at fabric stores, hardware stores, camping supply and military surplus stores, and in many hardware sections of discount stores like Wal-Mart. Loop the webbing around the loop on the clasp, and do the square/X stitch as above. Do this on both ends.
Fig. 3
Attach your straps in an 'X' pattern, or just to the rings on the belt loops. You now have your own bondage pants... too easy!

You can also do this with heavy skirts, shirts, jackets... you name it!