I found a cute candy jar being sold here in KSA that looks good for a Betta tank. The USB powered LED lamp feature was originally from Artificial Intelligence (https://www.instructables.com/id/The-USB-powered-LED-CD-lamp/?ALLSTEPS).
It's USB powered because this Instructable would look good on an office table, and you could always be with your precious Betta (or any other fish) at work.
Step 1: Cleaning and Gathering Materials
1. Eat the chocolates/candies.
2. Place your jar in a pail of water until the label is soft for you to remove without scratching the jar.
3. Dry it with a soft cloth.
1. soldering iron and lead
2. electric drill with 5mm bit
3. 7 LEDs
4. 7 resistors - 68 Ohms
5. hook-up wires (solid)
6. switch (optional)
7. USB cable (from a broken mouse)
8. 2 CD slim cases
9. mounting tape
10. rubber footing (don't know what it is called exactly, but these are the rubber footings from small equipments. i got mine free from a network hub)
11. candy jar of course (any type is fine, just use your creativity)
12. super glue
Step 2: Rubber Footing
Step 3: Mounting Tape / Double-sided Tape
Then stick some mounting tape of the same length on the outside so that you could install the CD cases on the roof of your jar.
Step 4: Installing LEDs on the Slim CD Cases
Use the electric drill and do some holes on your preferred location.
Insert your LEDs. Use super glue to secure them if they're a bit loose.
Take note of the leads (anode and cathode). The anode (+) is longer than the cathode (-).
Step 5: The Circuit
We will do the circuit in a parallel connection.
Solder a resistor to each LED's anode(+). Then run and solder the hook-up wire to all resistors so that all of these ends are connected.
Run and solder another hook-up wire to all the cathode (-) ends of the LEDs the same way as the anode.
You may refer to the diagram below (2nd pic).
For a more detailed approach, see the original instructable from Artificial Intelligence (https://www.instructables.com/id/The-USB-powered-LED-CD-lamp/?ALLSTEPS).
Chip off a small opening so that the two ends of the hook up wire (+ and -) can go outside (see comment 3rd pic).
After finishing the circuit, close the CD case (3rd pic). Check if the whole circuit fits well while the CD case is closed. If all is good, open the CD case again and peel off the remaining side of the mounting tape (inside) and close the CD case again. This will securely protect your circuit.
Step 6: Testing
1. strip off the end of your USB cable.
2. cut off the green and white wire and save the black (-)and red(+) wire.
3. from the circuit, temporarily connect the red (+) wire to the line where the LED's anode runs (the line where the resistor runs).
4. temporarily connect the black (-) wire where the cathode runs.
5. power on your computer.
6. plug in the USB and see of the circuit works (2nd and 3rd pic). if not, check your connections.
Installing the circuit to the candy jar (sorry, no pics)...
1. disconnect the USB cable from your circuit.
2. peel off the remaining side of the mounting tapes that are located from the outside of your CD case. stick it on the jar's cover.
Step 7: Installing the Switch (optional)
I've detatched the cover, drilled a hole and installed a toggle switch, then completed the ciruit permanently. You may refer to the diagram below.
And also I've drilled some small air holes at the back of the lid, by the way.
The toggle switch has two terminals. Solder both ends of the positive wire onto these terminals. See the 3rd pic for your reference.
Step 8: Final Test
2. From a powered-on computer, plug in the USB cable. Test the switch if it works.
Step 9: Add Fish and Enjoy!
I've placed some crushed corals and fake plants. You may use live plants too, but I'm not that sure if it will thrive on these LEDs. Added aged water, then the fishes.