Awesome suggestions, Don!

I share co-working space with a bunch of the Mozilla guys working on MozillaOS (they just ditched the name Boot2Gecko), and their demo hardware is mighty impressive-- it looks like they'll have a foreign launch first, but next spring some time we should be able to start playing with their phones. I hope they succeed because an html5 based system does sound like the bees knees.

Jeff and I have a conversation elsewhere where we were talking about laser cut black styrene sheeting as a mid-level between card stock and 3D printing. just cross posting for the record

Oh, sweet, thanks for the styrene link. MozillaOS should work fine -- however the web based version is fully functional (i'm adding offline caching so it can be used even without a web connection) and i expect as browsers catch up to Opera in implementing WebRTC features, it'll work with stock browsers as well. Luckily that means that when MozillaOS is ready, it should "just work" but we don't have to wait for it to get started.

Mathew, do you have an intuition of which thickness is a good folding thickness, or should i just order a few and try it out?

I think the 1/16" stuff-- .060", 1.5mm is pretty stiff but workable-- I'd check out the .040 stuff too, because its half the price. I think the biggest issue is light transmission, but I've only worked with the white stuff, so I can't speak for the black sheet.

if you score the interior of a fold, styrene sheets fold great. it might be possible to lightly zap the surface with a laser to "score".

I just updated my version of the 3D printable spectrometer: http://www.thingiverse.com/thing:28100

I changed the mounting angle to 32 degrees to more closely match the different gratings I have on hand. The 45 degree mount tends to throw the spectrum off to one side making it difficult to get a good photo.

In the end, while it does seem to work very well, the paper, PVC, or styrene versions will likely be more accessible to the majority of users. At least, until 3D printers become more popular.

Wow, that is super cool! A few things i was excited to notice --

so extrusion printing seems not to yield precise "slits" so you cut it with a razor saw? that's very good to know. For the PVC one I used a band saw and it work surprisingly well.

I was wondering about the mounting angle and expect that people may want it to be parametric. I was thinking of making a spectrometer on a kind of swivel joint so that you could collapse it down when not using it, but this could also let you choose an ideal angle. I'll upload a sketch soon.

I love the idea of nubs with rubber bands. I was thinking of adding an elongated tab to keep the device rigid and stop it from wobbling which throws off the calibration. I'll include this in my sketch.

I was also wondering if you'd be interested in reposting your Thingiverse post on the Public Lab site, mainly because then you'd show up in the "contributors" list on the spectrometer page, which seems proper and fair.

Thanks Brad, awesome contribution, and as always thank you for respecting the license and releasing under the CERN OHL!

Thanks Warren. This is actually the second spectrometer I have built. The first was part of my thesis and used 1.5" PVC and a hacked point-and-shoot camera. I have another one in the works that is controlled by an Arduino and uses the sensor out of a barcode scanner.

Some printers can do a very good job at printing slits but even the good ones tend to vary a bit which can make the spectral lines fuzzy. Cutting with a saw isn't too bad but the slit is still a bit wider than I like. I found that gluing a pair of single-edged razor blades such that their edges are facing each other and extremely close together can really clean up a spectrum.

I like the idea of a swivel. I may try one out this weekend and see if I can get one to work.

I wanted to add another brace along two of the edges to keep it from sliding around on my phone but worried about it limiting the number people who could use it. We could always make different mounting plates for different devices or make the plate over-sized and include an extra corner piece that could be glued on to make it a custom fit.

Ideas, ideas, and more ideas. This should keep me busy for a while :).

I'll get it added to the the PLOTS WIKI ASAP.

Awsome thing you have created :)

That's kind of what I'm thinking for a reinforcing plate and a flip-up tube.

Brad - the wiki is fine too but you can also post a research note if its just something quick -- like a blog post basically. Just so you know.

I'm kind of thinking the longer plate as pictured above could work well, esp. if combined with permanent double-sided foam tape. If you don't want to attach it directly to your phone, anyone can buy a case for their particular phone, and attach to that. I think some careful work on the shape of the joint could prevent light leaks -- maybe some kind of internal flange...

...but i drew the lower design wrong since it couldn't fold backwards past that flat part at the joint.

Jeff-- what about those soft silicone phone cases? They're cheap and I bet that the attachment plate could flange underneath a hole in one of those, so long as the flange extended in all directions (currently it just goes down.)

looks really nice and matte black -- but i've been thinking that the more rigid the case, the better -- the PVC spectrometer is mounted to a fairly stiff but still flexible vinyl-looking case, and the case still flexes easily, messing up the calibration. I wonder though -- if you cut the case open and lay the rigid extended flap against the phone, inside the case, maybe it'd be stable enough. I just don't want folks to have to adhere things to their phones directly if possible. I'll try a few different things... i bought some super-cheap pink phone cases on Amazon for $2 each, so i can make some mistakes :-)

Warren I just discovered you guys by the Kickstarter page. I like the work you are doing. You show your fold up design flipping all the way open so I made a few sketches and convinced myself to go the other way. Most cellphone cameras are in the back left corner and on iphone very close to the edge the spectrometer would have to be sticking off the cell phone to get at the right angle. The is two designs I did in sketchup it still needs work but it gives you an idea what I am working on. It can do various angles to work with different gratings. The design is roughly 4" X 1" X 1". If your interested in it I will send you the model or upload it somewhere when finished.

Hi, MFarmer - sorry your image did not load... can you try again? I'd love to see your design. Consider posting a note at http://publiclaboratory.org/note/add (after signing up at http://publiclaboratory.org/user/register)

I signed up yesterday but somehow missed your reply. I posted an image and the album link here: mobile-android-version-spectral-workbench

Fantastic work. This is a seriously cool project. I'm going to fiddle with my design for a telescope eyepiece phone mount http://www.thingiverse.com/thing:39144 . It's in two pieces (a phone case and a short barrel to slide over the eyepiece) that fit together with 2 formed pins. It may not be such a stretch to design the spectrometer tube to fit to the existing case.