This is a sketch of what I plan to do. Notice that the optical path will be the same as the original sensor.
For the acrylic tube, go to Ebay and search for acrylic tube. You will find numerous listings, all using the same illustration of a bunch of clear plastic tubes. Click that sellers "store" and you will find a listing for 1.5 inch tube. It would be cheaper at Tap Plastic, but they won't sell less than a 6 foot length, and that costs more than one foot plus shipping on no ebay links allowed I get my sheet acrylic from Home Depot. It is cheaper at Tap Plastics, but I have to drive 20 miles, and that costs gas! HD is very close to me.