Single floating gate transistor
Buy a normal FET, leave the gate unconnected. You now have a floating gate transistor :)

Less flippantly, this is actually one of the answers suggested to your previous question: connect a capacitor to the gate of a FET with some way of charging and discharging it. If you design the circuit to minimise the current leakage off the capacitor and use a large capacitor, you can store a bit for a long time.