Conservation of Mass
One of the limitations the designers deliberately set on themselves was that Transformers must abide by conservation of mass. In other words they cannot change in size from robot mode to disguise mode. This titbit of information dismayed me as it prevents some of the coolest Transformers from existing. But then I got to thinking of ways of preserving the original nature of particular characters within the mass conservation limitation (and of making some other changes too). What follows then is my own personal re-imaginings of particular Transformers rather than anything that may be in the movie itself. Think of this then as an alternate toy-line had I been creative consultant in some parallel universe.
Warning: Massive Transformers Geekery follows!
Soundwave: The original Soundwave is a larger-than-average Decepticon who transforms into a cassette recorder of normal size. The mass-conservation disguise I would propose for this character is a massive speaker stack complete with mixing desk that one would see at a nightclub or live music gig. Imagine the debut scene of such a character as all his components come together to terrorise a bunch of ravers!
Blaster: The original Blaster is a larger-than-average Autobot and the nemisis of Soundwave who transforms into a boom box. To make him different from my newly imagined Soundwave, and to have him conform to the standard of Autobots taking automotive form, I would have him transform into one of those TV news vans. This would allow him to still have signal transmission and music playing powers and also allow him to transport himself.
Reflector: The original Reflector was a gestalt of three (moreorless identical) robots that transformed into one handheld film camera. My re-imagining would be to have him as one Decepticon robot which transforms into three separate TV studio cameras. This would give him sufficient mass to be just smaller than the average Transformer.
Perceptor: The original Perceptor is a larger-than-average Autobot who transforms into a microscope. So to go from small to big I would have him transform into a telescope. Even better - is there any such thing as a mobile telescope - like a van adapted to having a mini-observatory on the back? Once more this would allow the character to conform to the Autobot standard of taking automotive form.
Megatron: The leader of the Decepticons is a larger-than-average robot who transforms into a handgun sized to fit a human hand (or sometimes a Transformer hand). The character has had a number of toy incarnations that have included a military tank. I would propose a compromise however of having him transform into one of those mobile cannons such as a Howitzer. In other words I am just making him a big gun. A similar thing could be done with the character Shockwave (who was originally a futuristic ray gun but in my imaginings could be an alien laser cannon)
Optimus Prime: The most well-known disguise for the leader of the Autobots is a truck cab (prime-mover). However he has had other toy incarnations such as a fire engine. The fire engine toy itself is way too blocky and plasticky for my liking but the concept works for me. Prime is a heroic and trustworthy character and a natural authority figure. Nothing fits this better than a fire engine. Compare this with the kind of characteristics associated with trucks! At best I think 'salt of the earth' but at worst I think 'trailer trash'. A truck would work better as some grizzled maverick sidekick (imagine someone with the body of Ultra Magnus but the personality of Ironhide) than as the wise hero of the story. 'Blasphemy' many will say. But consider how much kids love big red fire engines (the toy form of the character Inferno would work well for this toy). Also it would take care of the issue of Prime having superfluous parts (e.g. the trailer).
Constructicons: The Constructicons were the original 'combiner' group of Transformers that together become a 'super-robot' (Devastator). The thing was that as robot the toys were smaller than (say) the average Autobot yet the transformed into construction vehicles that are bigger than your average car. However since the time of the original toys, smaller construction vehicles have come into use - I have been seeing a lot of them lately as I pass Scroresby Freeway construction works and many of the newer bulldozers and trench diggers can fit on the back of a tray truck. So I would propose recasting the Constructicons as a group of five robots with one larger one and four smaller ones (rather than six smallish ones) - one leader robot as the super-robot body and four others as the super-robot limbs. This arrangement risks comparison with Voltron but makes for more functional toys (as was the case with subsequent combiner groups).
Dinobots: In the original cartoon the genesis of the Dinobots was a rather silly one. Basically the Autobots discovered some dinosaur fossils and then went "how cool would if be if we had some of these?". My proposal is that the Dinobots are like all other Transforms and have acquired modern world disguises. They could transform into the kind of attractions one finds at a monster-truck rally such as the 'Truckasaurus'. The Dinobots could be all angry then because of the embarrassing forms they had been given.
Insecticons: In the original cartoon the Insecticons had been stranded on Earth for millenia and had "evolved" into having larger-than-life insect disguises. My alternative is for them to have deliberately taken on the disguise of huge modern art sculptures resembling insects made from discarded bits of machinery that one sometimes finds in civic squares. How cool to then see these things come alive and cause panic!
Jetfire: Jetfire (Skyfire in the cartoon) was a huge Autobot who transformed into a jet plane (he was a rip-off of the Robotech Veritech Fighter). I personally like the way that Autobots were made underdogs by the fact that most of them were just cars while a lot of Decepticons were jet fighters. I can see the need for a token skyfaring Autobot but maybe this character would work better as a helicoptor (thereby getting more variety of form into the collection). Some helicopters are massive (e.g. the Sikorsky S-61) so I would happily recast the character thus.
Other Decepticons and Autobots: If the standard Autobots and Decepticons transform into cars and jetplanes respectively then Autobots will be smaller than Decepticons. Is this a problem? I think it may contribute once more to the postive 'underdog' status of Autobots. However I think one would want to limit the size difference between the two. I suppose one could both find larger forms of car and smaller forms of plane to assign to the characters. The other thing I like about this distinction is that it emphasises that the heroes take civilian form while the villains take military form. Call me a pacifist but this seems cool to me.
Well I have rambled on plenty on this topic so it may be time to go and play with my Transformers now...