We could but not sure if you are willing to pay the price.
A project like that from strt to finish is ALLOT OF WORK. :wacko
To have something like that sculpted, moulded, detailed, casted, trimmed, sanded, prepped, then painted + the cost of labour and materials to make the moulds and the casting... wow... :confused In fact just thinking about it i think i withdraw that we could do it. We can, but.. No. :confused
What TMP said... even though it would be uber cool (and I'd want one, too), it's quite a massive task and expensive even to get something remotely decent. :unsure
You could try with a vacu-formed armor with rubber/urethane joints and gloves... This could be a nice option... But if you want to make it killer, you should make a nice foam latex appliance for your face!
I have wanted to make this for years. I have a number of projects that I know I want to work on before this would be a possibility, but I'll keep it in mind.
Ramiel's right; some kind of shiny plastic looking mask would absolutely top this one off.
No matter how nice the suit is, I think that the face would make or break this costume. I would go for prosthetics, so that you can have an articulated face. At least a prosthetic chin. Then glossy make-up to give a plasticy feel.
The armor could be sculpt in cardboard and/or construction foam (the blue or pink variety). You can reinforce it on the inside with papier-maché or even fiberglass, and then fill gaps with bondo on the outside. You could cast it in fiberglass later.
There are various threads on this forum that show examples of such construction techniques. A quick search gives me: Master Chief, Durge, How to make your own spartan helmet, Making a cardboard jango/boba helm.
I remember seeing a fan made Buzz outfit a while back that was pretty well done. They used there on face, no mask, and added the chin dimple and rosey checks. I've got it saved on disk somewhere. I'll see if I can dig it up.
I just remembered the "full size" (if Buzz Lightyear were a person rather than a toy) animatronic version in the ride queue at Disney World. I thought it was really neat to see him for "real".
Just think: somewhere, there are molds for those parts.