Reverse thrust will probably never appear on todays micro-turbine engines considering that thrust reversers are used on turbo-fan engines. They redirect the By-pass air from the fan set. Microturbines are turbo-jet engines that have no fan by-pass. Therefore if there was a thrust reverser it would look similar to the one on the UPS aircraft (in the post above) but one will probably never be made due to temperature limitations of model aircraft (heat transfer through such a small piece of metal into servos and such) and the high back pressure effect that the reverser would cause in the engine which would probably lead to severe damage.