Build difficulty: medium
1. You will need a condom and a length of pipe insulation foam.
2. Measure the insulation foam against the condom and cut to size.
3. Cut the insulation foam in half down the middle and carefully shape the inner semicircles so that they fit you.
4. Attach the tip of the condom to a rubber bath plug and lay the condom inside one half of the insulation foam.
5. Put the 2 half back together and hold in place with extra-large hose clips. Rubber bands can also be used.
6. Pull the end of the condom through and fold over the end of the foam (above). The friction should hold it in place but a rubber band can be used to secure it.
7. Adjust the position of the rubber bands / hose clips to allow for comfortable entry. The condom and rubber bands will create the tension to maintain pressure on your cock.
8. The two halves of the foam will separate to accommodate you as you enter, while maintaining firm pressure.
Here is a variation that incorporates a latex glove as the contact surface, uses bubble wrap to soften the flesh, and rubber bands to hold the body together and create tension.