This rig is made with four mirrors and is basically two periscopes turned sideways.  Below is a picture of a small one made for the Q-Cam using cardboard and wire.  For the large one you can simply bend some sheet metal into L-shaped brackets and duct tape the mirrors to them.  The brackets can then screwed to a piece of wood for a base. The two outside mirrors should be able to be rotated a bit for good viewing and you will probably need to bend the brackets a bit to get vertical alignment correct.
    6inch square mirrors cut from a single 1ft square mirror tile worked well.  This is perhaps a little bulky, maybe 3inch squares would be okay but it is easy to align the bigger ones and may give a better 3-D effect for the distances usually shot outdoors with a video camera.
    In fact during construction of the first one of these I discovered something interesting.  In order to get everythning lined up it worked best to place my nose where the center of the camera lens was going to be, aim the mirrors at the scenery and start twisting and bending things into line.  When I got it right the 3-D depth of field of 8 or 10 feet associated with normal binocular vision was extended to what appeared to be 50ft or more.  Presumably this is at least partly due to the mirrors giving an effective 15inches or more of separation between eyes.  At any rate when you get a good view in this fashion you can then put the camera in place.  It will probably be necessary to rotate the outside mirrors to a bit less cross eyed position  to get the in the cameras viewfinder to look acceptable but the vertical alignment should be okay.  I mounted the camera to a separate piece of wood  which was in turn bolted to the mirror assembly.  The whole thing is of course mounted to a sturdy tripod.  Be careful as it is easy to tip over.