No fancy machines or gadgets needed here. Just hard work and some free weights with a lot of sweat to give your abs that desired six-pack appearance.     

Lay on the floor and hook your toes under a solid object like a couch. Bend your knees at a 90 degree angle. Place your hands behind your head. Rise up about a foot off the floor and go back down. keep repeating until you feel a slight cramp in your abdominal muscle. Rest for about a minute laying flat on the floor. Then repeat, this time moving your right elbow towards your left knee only coming a foot off the floor until feeling a slight cramp. Rest again laying flat on the floor for about a minute. Then repeat, this time moving your left elbow towards your right knee until feeling a slight cramp. Rest for a minute.       

Lay flat on the floor, hands behind head, legs flat on floor, knees together. Raise knees toward chest as far as they can go, keep repeating until you feel a slight cramp. Rest laying flat on the floor for about a minute. Next move your knees to the right while back is flat on floor and raise towards chest. Repeat until you feel a slight cramp, and rest for about a minute. Then move your knees to the left, repeat the same motion until feeling a slight cramp. Rest.       

Next lay flat on the floor, knees bent at a 90 degree angle. Bring right knee towards left elbow while bringing left elbow towards knee. Repeat until a slight cramp. Rest laying flat on floor. Then repeat with left knee and right elbow until slight cramping. Rest.