Time to find some parts for the 3-Cell
Grips
Reference photos show the saber as having seven grips around the bottom tube with the ends cut at an angle, made from a black T-track material. I have never seen a vintage part that exactly matches what appears to be on the prop, but I have seen some that come close. Usually described as sliding door track, and made of plastic. The t-track has been called many different things over the years, like windshield wiper blades and most recently by Roger Christian as a type of car weatherstripping, but as research from the great people here over the years has concluded they are most certainly a plastic material. Being that there isn't a current reliable source for vintage t-track I turned to the aftermarket.There are several sources for saber grips but as far as I know only two that make them out of plastic, Roy and Gino. I have used several sets of Gino's grips in the past based on their reputation and the research put into making them so that is what I've selected for this build. I also own a set of Roy's grips and they are top notch, you can't go wrong either way, with the slightest of an edge to Gino.
D-ring and clip
There is no known reference photo that clearly shows what the profile of the clip is and how it is attached to the bottom of the hilt, it can only be guessed at. The size and shape of the D-ring are ,luckily, fairy easy to surmise. When looking at vintage parts to try and find something that would work, pointed out by member Sym-Cha, and that is the D-ring and clip attaching handles and on the sides of some Graflex camera cases. Although not attached to the case the same way it is on the lightsaber, the size and shape of the D-ring, it's finish, the finish of the clip, and the profile of the clip when removed from the case and folded over, look incredibly like what is present on the prop. I have been looking for a couple of years now to try and acquire one and the only cases listed for sale that have the proper ring and clip have been listings with full camera kits and garnered $500+ price tags, a bit outside my budget for a D-ring.
Now I'm not saying that I know for sure that the case clip and ring are what's on the movie prop but I think it' a pretty high probability. It could also be a custom made part by the production team. And with that said I'll bring up the best option for an aftermarket part, and what I'll be using in the mean time while I wait for an affordable vintage part.
Designed by Sym-Cha and sold by Roy I think its the most accurate reproduction piece available.
If anyone has a line on a vintage D-ring and clip I would be forever in your debt.
Exactra Bubble display
Finally we get to the bubble strip found in the clamp of the Graflex. Here is a known vintage part, found inside Texas Instruments Exactra 19, Exactra 20, and TI-2000 calculators. It is a 7-digit bubble magnifier strip for displaying the numbers on the calculator.
Here's where it gets tricky. There are two disticnt types of strip to be aware of when acquiring a bubble strip or calculator. First there's frosted with all round bubbles, second is clear with small flats on the sides of the bubbles. There is also a difference in how the two types of strips are mounted to the circuit board in the calculator, as well as their overall profile.
Here's a wonderful thread detailing the different calculator bubbles
http://www.therpf.com/showthread.php?t=73545
Now which is used on Luke's saber? Back to the reference photos. The clearest shot of the bubble strip is in the infamous toe pic.

Distinguishing between bubbles with or without the flats on the side is difficult, but I do think I see a frosted backing, especially when I compare what each version looks like in a Graflex clamp. Furthemore, the frosted bubbles have a rectangle underneath where the calculator display fit into, the clear does not, and I believe you can make this rectangle out in the toe pic here which I've highlighted, poorly, and can be seen in the previously mentioned bubble discussion thread.
Once again there is no way to know for sure which bubble strip was used, this is just my best educated guess.
Assembly time!