Hey Hoppy, sorry I didn't actually mean a lens literally. Yes, it's supposed to be a piece of frosted acrylic plastic. I was going to keep it as a surprise in case if it didn't work but the idea of the undercut is to make that sheet swappable for testing purposes. See the first post for an updated cutaway.
If I end up building the updated version, I will definitely integrate the new filters you've suggested. I've already bought the Rosco filters so I think I'm stuck with it for now. By the way, this version is optimized solely for the swapable acrylic sheet and ease of adjusting the thickness of the calibration spacer. The idea is to figure out if the acrylic top can be 3D printed as a part of the housing (no sealing on the top!) and if a very precise and repeatable calibration spacer can eliminate the the need for calibration in the future (I bought 2 sensors for this purpose). I have other ideas in mind for future improvements (reduced assembly time, improved sealing, etc.).
I was going to use what you used, Weldon #16, to cement the housing. Supposedly it can bond acrylic to a host of other plastics. As for the electric cable to the housing, I haven't decided yet. My fall back is to mix Weldon #16 with acrylic dust and form a bead around the seam between the cable and housing. In my next version (if it's built), I plan to have a nipple extend from the wiring exit with a small lip and use adhesive lined heat shrink.
By the way, supposedly the 3D printed black nylon is not waterproof so I might even bother sealing it at all unless I can find a suitable potting material. The 3D printed frosted acrylic IS waterproof though but more expensive so it's more appropriate for the next version.
Last edited by Jalopy; 10-12-2013 at 08:50 AM.
Reason: Housing material.