While a Stormtrooper armor can be heavily modified, trimmed and altered to fit a range of body types, the Protocol Droid costume does not allow for such large modifications. There is possible to widen for instance the belly area of the torso, the arms, legs and shorts, but only as to gain a few inches. Because of this fact, (unfortunately) only a special body type can fit into such a Protocol Droid.
I was terribly nervous of not fitting into the costume at all, especially the torso. Before I ordered my parts, I got to try on a right leg of a 4-LOM costume which belonged to a fellow Garrison friend. It fit just perfectly, but when I was to try the torso, it left a large gap of at least 3-4 cm on each side of my chest, and the two halves (front and back) would simply not bolt together at all. The 4-LOM (except the head) should be quite identical to C-3PO both in size and height.
Luckily for me, the screen accurate type of protocol droid torso comes in two sizes, “small” and “large”. The larger torso was made as to improve the actor’s comfort during filming, and it is slightly enlargered around the chest area. The small difference in circumference between the small and large torso should be unnoticable for an untrained eye :). I waited patiently for this torso for 2 months till it finally arrived.
It was my only hope. If the torso wouldn’t fit, I could’ve easily terminated the project. What good is a static display piece just standing in the living room? The most enjoyable part as a costume enthusiast is to be able to wear his/her favourite costume, to stay in character and interact with people, am I correct or not?