here is my attempt to explain what i did on this, hope this clears a few things up or give you even better ideas.
if you tend on trying this, take in account that it could go horribly wrong and the figure will be ruined.
You WILL need a set of PPC-T01G ball joints ( you can get them at hobby link Japan) or something similar.
an exacto knife ( a lighter of some sort of flame to heat up your knife is helpfull too)
a drill. (remember to go slow here drilling to fast might break the plastic, also play with the forward and backward setting. If you have no experience I strongly recommend trying to drill holes in small plastic objects to see what might happen.)
glue
screwdriver
fine saw blade
and a lot of patience.
1. Elbow and Wrist movement.
the elbow thing is based on a tweak I saw on tfw2005 but I decided not to cut up the upperarm to get elbow movement but just use the rotation of that big wheel on Rampage's arm
there is an extra medium sized ball joint there allowing the hands to be posed in all directions while the elbow only allows a rotation over one axis.
take the saw and cut of the hand . its very important that the fake plastic wrist joint stays attached to the hand, this will become a real wrist joint later.
I used the saw until here and did the last partwith an exacto knife, so there is no visual damage to the joint bit.
this is what it looks like detached.
the top part of the arm where the hand used to be attached you can now saw off.
(it is important you do the steps this way otherwise there is no decent way to detach the hand and keep the wrist joint intact)
Now its time to make some holes
Make sure that you measure correcly where to drill the hole otherwise stuff might get in the way of eachother.
Also use a correct size of drill, this way you won't need glue to keep everything stick together.
Remove the platic pegs inside the wheels so they can turn around.
drill the hole for the wrist ball joint.
extra trimming might be nessecary to make everything turn smoothly.
a fake joint becomes a real one
carefully drill a hole here too.
attach the hand to the shoulder
Rampage's new heels.
From day one I was annoyed by these useless things hanging on his upperleg. they have no function in any mode, except getting in the way.
Now you can put them to good use by making them into heels so Rampage can at least manage to get to the bathroom by himself without falling over all the time.
because rampage isn't very heavy , the small heel gives the proper stabillity to make him stand on two legs
remove the pin
slowly remove the slot
A = keep this peg otherwise rampage's knees wont work anymore
and now you've got a fully functional , stand alone Rampage.
notes:
I made a little mistake with measuring the pivot point of the joint so I need to detatch the heels when transforming him. although it should work in the transformation if all the parts are on the correct place. Im not planning to transform him a lot so I don't mind.
I also added a hip joint because it helps for stabillity that he can tilt froward a bit. I don't know if it is really nessecary though.
(don't add a joint that is too loose)
good luck