Goode6 was interested in cutting down windshield. Here is how I do it but I learned about this from the CalSci site. Flatten a cardboard box and push against the top of the existing shield and use a Sharpie to draw a line on the cardboard of the top curve of the shield. You then use scissors to cut the cardboard on the line. You now have a pattern of the top of the shield. Next, use blue painters tape on both sides of the shield from the top to well below the acrylic you will remove. You can use short pieces of tape and put plenty of it on. The tape will prevent the acrylic from chipping. Then hold/tape your pattern and measure vertically in the middle of the shield and draw a cutting line about 1/2 inch down from the top of the existing shield. I don't mind doing this several times rather than cut off too much material. Then use a saber saw with a fairly fine blade and cut along the line on the tape. I have done the cutting of the shield off the bike braced on soft furniture in the house but have also done on-bike but then I really hold the shield with my left hand very close to the cut to reduce the vibration. I cut on the front side to cut fairly flat with the shield curve. Leave the tape on the shield and use a file to smooth the cut. Remove tape on the piece you cut off to see what the top looked like and duplicate the smoothness and look of the new shield top to the old.. Get the new top real smooth with the file and round it some on both front and rear. . You may also need to use the file to round out the curve on the sides. Remove the tape. Use fine steel wool to further smooth the new top. Then, use a cleaner such as Novus. Novus has a cleaner, a fine scratch remover and larger scratch remover paste. Never use any paper product to clean the shield. After all this, ride some to see if you want to cut more. I cut mine so I can see the ground about 50 ft in front of the bike but can see a lot closer if I sit up real tall and straight. My goal was to never have to look through a rainy helmet shield AND a rainy wind shield at night. This is an easy job but the blue tape and the pattern are the keys to a good job.