The Dams Raid is well represented in artworks, but one of the most common errors made is the depiction of the altimeter spotlamps. These are often shown shining down directly beneath the aircraft where, of course, they could not be seen by any of the crew! In reality, the lamps were aimed out to the starboard side where the two beams met ahead of the wing, where they could be seen by the navigator who was looking through the blister on the side of the cockpit canopy. When the light spots came together on the water, the aircraft was flying at the required 60ft drop height.
The two light spots are also often shown the same size but, as the rear beam had further to travel, its spot would have been larger. Although the location of the forward spotlamp is known (it was in the bomb aimer's camera position), there is no certainty over the location of the rear spotlamp on the aircraft; however, the best evidence and most convincing argument supports it being fitted in the (unused) ventral gun position behind the bomb bay.
Airfix produce a fine 1/72nd scale kit of the Dambuster Lancaster; one version of this comes with a vacform dam intended as a stand for the model (although this is out of scale with the aircraft). However, I realised that the spotlight beams themselves could be used as a stand, and set about making a diorama to demonstrate the correct beams while also using them to support the Lancaster.
The finished model uses the Airfix Lancaster with some enhancements (and corrections) - notably improved Upkeep gear, all (visible) crew figures (added Navigator, Bomb Aimer and Front/Rear Gunners), radio aerials and "spinning" props. The light beams are cast from clear resin, while the base is textured glass painted blue (underneath) and mounted in a wooden plinth 18"x18"; the "light spots" are unpainted, allowing the beams to be illuminated from below. (Pedantic physicists will note that the light beams themselves are actually invisible, but I claim artistic licence in this respect.)
A few more pictures of the finished model, both "day" and "night":