You might try this: on a quiet road, or empty parking lot, accelerate HARD in first gear, but only momentarily (like a half second), then ease off the throttle and smoothly disengage the clutch, and let the car coast to a stop, without applying the brakes... The whole point being to get the dice to slide rearwards - coasting to a stop hopefully will keep the dice towards the rear of the ducts. Once stopped, set the handbrake and get out of the car, move the seat as far forward as it'll go. Then with a flashlight, have a peek into the ducts and try to fish it out?
It's either that, or you need to remove the front seats (disconnect battery first or you'll get an airbag fault when you replace the seat), center console, and forward carpet to get at the duct.