Eric,
There are quite a few companies that will apply a layer of aluminum to cuben fiber or almost any other substrate supplied by the client, but I found that the cost was prohibitive. You can find these companies easily online.
There are two basic processes available: thermal vapor deposition and sputtering. The aluminum on most radiant barrier films, like space blankets, is applied by thermal vapor deposition. Aluminum is evaporated from a heated crucible and the vapor condenses on the plastic film. Heat in the chamber can be a problem. My first sample melted a little and shrunk into a ball. The aluminum layer tends to be thin and adhesion is relatively poor. It abrades away pretty easily. I found that getting enough cuben aluminized to make a bivy sack costs about $1500 by this method. Tooling (set-up) fees are high, so the more you have done, the less it costs per square foot.
Sputtering is the second method. Sputtering machines can’t generally accommodate wide pieces of film, so it has to be done in small sections that you’d have to join later. Sputtering uses a magnetic field to erode a solid piece of aluminum and deposit aluminum ions on the cuben. The metal layer can be thicker, and adhesion is much better. The aluminum surface can be made pretty durable and very uniform (like a mirror, much shinier than a space blanket). But sputtering is very expensive. I did a lot of hunting and found that enough cuben to make a bivy couldn’t be sputtered with aluminum for less than $3500.
I don’t know if an aluminized piece of cuben could be colored more easily. If the aluminum layer itself were covered with color (dye or pigment of some kind), it wouldn’t reflect radiant heat very well.
I think aluminized vapor barriers are underexploited in insulative gear designs (sleeping bags, bivy bags, apparel, etc.), but polyester space blankets and polyethylene “heat sheets” might be the only options for the MYOG crowd for now.