Until the end of October is a long time. So no need to hurry. Anyway, we want to see some progress - soon 
Glad to see you have a design in mind. I like the Larry Light idea. The trench could be filled, or just leave it and attach the leds on mcpcbs right into it, with a plastic cover. A lot of things could be done. Line it with copper, or brass sheet. I'm sure you will come up with something as you go along with it.
Okay, another update in the OP.
RBD, thanks for the offer. I have some of those heat-sinks around also. Maybe some day I’ll have a use for them.
ImA4Wheelr, I’m sure you’ll think of something. 
fritz, here you go. Progress is being made. I’m not worried at this point about finishing. Last year I got to a hang point that I just didn’t get past in time. This year, I’m confident I’ll at least have it working by the end of the contest, even if it isn’t exactly what I’m hoping for.
O-L, they say great minds think alike. Well, I guess ours do too! See in the OP the lens I made for the LEDs, to cover the trench. If I can get the epoxy to go where I want it to, and nowhere else, it should turn out looking okay.
Edit: Hot off the presses! I just had a thought about the driver. (read the OP for a clue about what I’m talking about here) Do you think I could make a copper pill? I was thinking that maybe I could drill out the bore of the tube just enough so that I can make a two-layer pill out of copper pipe. I’d cut a ring of 1/2” for the inside “shelf” and solder that into another pipe, or coupling, or whatever, to make the pill fit in the tube very tightly. I need some kind of end caps for finishing the two ends of the tube, so the pill can be made to stop at the end cap, and the spring(s) for the battery will help make sure the driver stays seated in that pill. Hmm… Will it work? I know there are lots of guys on here that could make something like that. I’m just trying to figure out if I can do it with the limited skill set that I’m working with.
There are lots of other copper pipe diameters besides 1/4, 1/2, & 3/4 so something should fit. You can anneal copper on the stove to soften it, cut it open, and form a disc you can solder to pipe to close up the end. Some places sell such sizes in rolls or by the foot so you don’t need to get much. Also, there are other driver sizes both boost and buck besides 17mm. Lots of ways to close a tube besides threaded caps as well.
If you have loose 7135’s you don’t even need a pcb, just glue them together and wire them up.
Nice nice 
Looking great so far, I am looking forwards to more!
Regarding your question - maybe you make copper/ brass ends for the Aluminium tube. That would probably even look nice. Otherwise thanks to oshpark it is no problem to design a cheap custom driver by yourself. Also Mattaus made some amazing eagle tutorial videos: Eagle Video Tutorials BLF Style So maybe that’s a possibility. You could even try to merge the driver and the led PCB into one thing and then just screw that into the groove.
David
http://pbar.fnal.gov/organizationalchart/Leveling/2004%20water%20cage%20work/Cutubehandbook.pdf
Pages 21 through 25 will cover ID and OD of most all of the Copper Pipe you can ever find. USA that is. There are three main typed of Copper pipe Type K, Type L, Type M and the thicknesses are different for all of them. These tables helped me out a lot.
Also, here's a quick sheet too
http://www.petersenproducts.com/Specifications/Pipe_Copper.aspx
I’m sure you will nut it out. looks good so far with lots of bits. :+1:
Thanks for all the responses, guys. All of these suggestions are going to be helpful to me - even the ones I don’t use directly in this light. But, I have to say the one that surprised me is the one about using 7135’s without a driver. I have to say that would NEVER have occurred to me! You know what? This tube is just long enough for a xx650 cell, if I don’t take up any room for a driver. AND, since I dug a trench in the aluminum instead of just a groove, I have plenty of room there for 7135’s along with the LEDs. Hmm…
fritz, I just caught this, after reading your post again.
That’s actually a very good idea! I’m not sure there’s enough time in this contest for me to both learn how to design a custom pcb and get it ordered and delivered from OshPark in time to actually build the driver before the deadline. Maybe if I’d had even the tiniest bit of experience I could do it. Makes me wish I’d learned Eagle before now (I knew about the tutorial).
Fastech has 20 mm stars with a 7135 and reverse polarity diode pre mounted but they’re for souel LEDs. One of my first solitaire mods I soldered the 7135 ground tab to a copper disc with a 10mm star stuck on the other side(before copper sinkpads) B+ to led + and the pwm pin led pin to led and ground to B- . Takes very little space and an on-1, on-2, off switch and resistor can give you 2 modes without any other parts.
I had a look at the tutorials a few days ago and it’s not that hard to get started. At least the basic things are simple. You just need part 1, 3A and 3B that’s around 25 minutes in all and of course you are welcome to ask here.
Here you can download (again thanks to Mattaus!) the needed parts: Eagle Libraries
I for my part have to say that I am really happy that I learned it. It is easier than expected and will be so useful for this as well as future projects. Additionally OSH park is so cheap, three copies of your board with shipping are around 3$…
Another little update in the OP. I’m still trying to decide on a driver (or driverless) configuration, but I had other things to keep me occupied for a little while, so I kept moving forward. Pretty soon, I’m gonna run out of things to fiddle with, and I’ll have to do something about powering this thing up.
To hold the magnets in line while the epoxy sets put a plastic bag between them and a straight piece of steel. To make the driver a tight press fit roll a piece of copper wire into a ring just larger than the tube, solder it to the driver, and sand it until you like the fit, should only need it on one side.
To anneal copper or brass it needs to get red hot(glowing) before it softens and then it hardens again as its bent and shaped, sometimes needing annealing again to continue. Simply loading it with weight probably won’t flatten it, it needs to be rolled like dough with a large, smooth, heavy pipe. I use a section of brass pipe with another longer one inside as a rolling pin.
Figures… I did it all wrong! :person_facepalming:
Well, POO-POO! I don’t have any loose 7135’s laying around. I thought I might, but I don’t. I don’t even have any extra linear drivers from which to rob a few (By which I mean that I have a couple linear drivers here, but one is already slated for a future project, so it can’t be robbed, and the other has already been robbed of most of its 7135 chips, so I don’t want to rob it any more). I guess the driver situation is on hold until I get a clue. :weary:
I’ve got more than I can use if you want some. Not long ago I didn’t know squat about annealing either. Google is my friend.
One subject I find has not been addressed by the rules of the competition - spinning metal. This method is used to create objects using a wood lathe to create objects from sheet metal. It is in many ways inferior to using a metal lathe. Is spinning handmade or machine made? In my case I would use it for the driver housing.
I think they just list tools rather than worry over how they’re used.