I got this from a book of homemade sex toys: Cut both ends out of a can, put a few tube socks inside of eachother (more socks = more tightness) and put that inside the can, with the opening fitted over the mouth of the can, put a plastic bag of some sort (like a large sandwich bag) inside the socks, lube it up with some baby oil, and fuck away! It helps to put it inside a towel and place it between a mattress and box spring to hold it in place.
Take 1 melon/water melon, cut a hole in through the skin and flesh but leave the seeds in the centre, hole diameter to give a snug to tight fit for your erect cock. Microwave the melon for 10-15 seconds ONLY, just to take the chill off it - TOO LONG AND YOU WILL SCALD YOUR COCK!!! - not recommended! When you fuck it the slimy seeds feel better than a Fleshlight. Try also cutting a hole in one of the sharp ends for a different feel. Having said all that the two best appliances by far are 1. A slippery ****. 2. Your hand, this by far the most versatile!