Here is a lightsaber that I modeled from a few different sources, modified to fit the size that I wanted, designed a circuit for, and assembled. I 3D printed all the relevant parts for the hilt and blade cap on a Prusa mk3 3D printer, and the electronics and blade tube were sourced from The Custom Saber Shop.
The parts I ordered were an LED driver to regulate the current, a Luxeon Rebel Star LED, a small collimator lens to spread out the light, and the holder to connect the LED to this collimator. The part #s are:
78TW - A Thin, 7/8" Thin walled opaque Poly Carbonate 40" long piece of tubing ($9.25)
Buck700N - A BuckPuck 700mA 4-wire ($13.99)
RSredor - Luxeon Rebel Star (Red-Orange) ($6.89)
Coll87 - Collimator Lens 8.7 deg viewing angle ($2.50)
CREEHLDR - Cree/Rebel Lens Holder ($0.75)
Step 1: Testing Electrical Components
This was my first time making a lightsaber, so I wanted to keep it as cheap and simple as possible, while maximizing the visual result. I chose to leave out any audio or programmable components, since that doesn't directly add to the visual appearance and drastically complicates the electronics. For this build, I simply used a 9 volt battery, a toggle switch, and the aforementioned 700mA LED with a complimentary LED driver to ensure correct power draw from the 9V to power the LED. If you use a different led for different colors, be sure you choose the correct driver and adequate power supply.
CAUTION: Avoid looking at these LEDs directly, they're very bright and not great to stare at.
I have no passive cooling built into this system, and since its powered by a simple 9V battery, I highly recommend not leaving it on longer than a dozen seconds or so at a time. It could potentially overheat, as well as very rapidly drain the battery. A few experiments I found online estimate that this arrangement will drain the 9V battery after 14 minutes of continued usage.
The circuit I used is drawn up in the first image. Follow the positive and negative conventions labeled on all components, and it should be easy to assemble.
I merely inserted the LED into the collimator lens holder and taped it to the bottom of the tube to get test the appearance in the last picture.
Once this step is complete, move on to designing your hilt with the internal components in mind. Here I only had to account for the blade, LED driver, LED, battery and switch, but more advanced builds that incorporate micro-controllers or speakers will need additional planning.
Step 2: Design and Fabricate the Hilt
Here I lifted a variety of 3D models from thingiverse, eventually mashing them in together in MeshMixer to get something that looked how I wanted. I then subtracted 3D primitive shapes from the core of the handle to create cavities that would fit all the components that needed to go inside, such as the 9V battery, LED driver, tube, and switch. I measured each part with a calipers to make a 3D shape with similar dimensions, scaled them to 105% to account for printing tolerances, and then boolean subtracted them from the hilt to create the necessary cavities. I highly recommend Meshmixer for operations like this, unless you are modeling your hilts from scratch in a program like Inventor or Solidworks.
After design, I 3D printed each component, test fit them together, and then applied a couple coats of silver Tamia spray paint, followed by a couple clear coats to prevent scraping off the silver.
Step 3: Reassemble Circuit Within Hilt
Here I recommend checking the electronics one further time before embedding them within the hilt, so you can be sure that, if things don't work after, that you may be able to fix it by troubleshooting.
Here I ran the wires through the hilt. aligned all the components, and embedded the LED driver within the top part of the hilt before super gluing the top and middle components together. Shown in the second picture, I connected the LED Driver to the 9V connector, and soldered together all connections as well as the switch. Then I pressed all wires inside the hilt, as well as the battery.
Then I soldered on the LED to the LED Driver connections, and tested the light again to ensure I hadn't broken anything. Soldering the LED to the wires was difficult, and flux is essential to get it to properly wet the solder onto the pads.
Step 4: Final Assembly, Leather Wrap, and Wall Mount
Here I slid the third piece of the hilt down around the tube + taped-on collimator lens/holder, and press fitted it onto the LED to ensure proper alignment. Then I pushed the hilt piece into the pre-modeled groove in the middle part of the hilt to hold everything together, and super glued the cracks. After drying, the hilt is complete.
The final two touches were a semi-spherical piece with plug that I printed in transparent PLA. This slid into the end of the blade, and allows the light to reflect back within the blade as well as preventing the LED from shining out of the end like a flashlight.
I had a scrap strip of leather laying around which I cut into three strips and wrapped around the hilt, covering the 9V battery, and holding everything in place. This was also super glued, but you could also use contact cement. If I need to replace the battery in the future, I will need to remove the middle strip and reattach it after replacement.
The last step I took was to quickly model two semi-circular mounts to hold around the handle and blade so I could mount my saber on the wall.
Step 5: Enjoy!
I hope this rough walk-though was helpful. I highly recommend experimenting and learning from this, and make something original on your own! As always, be safe and use proper ventilation techniques.