In phun, if you want a prop that just looks and does the same thing as a segway - e.g. keeping a weight upright and transporting it using only 1 set of wheels, you can just add a large, invisible weight below the hinge to make the segway have a low centre of gravity. However, I found making a true to life segway a very fun project. Here are the steps to making one that would basically function similarily to a real segway.

A real life segway works by measuring your position to the ground, and adjusting motor speed to correct any balance disturbance. The problem in phun is that you can't yet include robotics into your machines, so you have to make use of the tools you do have.

1. Create a small rectangle, which floats from your plane at the height you want the radius of your wheels to be.
2. On one side, draw out a circle, give it a hinge, highlight it and send it to the back layer.
3. Copy both the circle and the hinge, and move it ever so slightly to the right/left.
4. Give Circle A collision A and Circle B collision B.
5. Highlight both of the hinges and give them a fast, strong motor...
6. then, make sure that the left hinge is spinning counter-clockwise and the right hinge spins clockwise.
7. Attach a weight to your segway and start the simulation.

Like the real thing, this segway will respond to tilting. As the segway tilts to the right, only the right wheel makes contact with the segway, which makes it correct it's balance, swinging it over to the left. Feel free to nudge the segway as many times as you like.. it will keep standing up.

Imagine what other uses in Phun this system could provide...