here is the thing;
I do a lot of work late at night in my computer, i love to design in the dark, but using photoshop shortcuts gets complicated, so i decided to do something about it , at first went for a lit up keyboard ... naah too expensive, (being a diyÂ´er, everything is doable... therefore expensive)
found this Instructable and eureka ...lol
https://www.instructables.com/id/Illuminated-Keyboard-Hack/?ALLSTEPS

first i thought the power of the LEDs (green lites with 3.v.) was not enough to power my high brightness or superduper leds as the proper commercial name goes. (4.5v?)
so i took power from usb port easier for me .

parts ...
clear acrillyc rod, round is better but since my led bar will be underneath my desk i chose a square rod
six or seven or nine leds , it all depends my bar is 20" (51 cm) long so i used 6 leds 4" (10 cm) appart from each other ..sort of
enough cable to connect the leds , you will need at least 25 " ( why the hell are you still using inches ??? 65 cm)
use the red and black cable , it is imperative that you have to use red and black or else forces unknown of the universe will mess up your life, or go with any color you like.
1 kill switch ... any kind, mine is really small 5mmx10mm (imperial equivalence.. guess it)
you will need a clear ...CLEAR epoxi glue , see the pictures, silicone will work too, but is waaay slower.
double sided tape , to fix in place.
one slice of key lime pie ( you will get hungry.. i was!)

tools:
cutter, exacto, carpet knife... get the point?
cable stripper (lol one girl dancing for the cable ...)
electric tape or thermofit or duct tape or masking tape.
pliers to cut led legs
a 7mm drill bit (1/4 ")
electric drill or manual or robotic... press drill is better.
sandpaper the coarser the better
soldering gun and accessories
a spoon.

Step 1: Go for It

first step.
i used a steak knife, it was really sharp and thin (good thing) to "mark" grooves on the acrillyc at the desired lenght you can use anything you have at your disposal as long as it leaves a clear groove in the acrillyc 1mm deep ... 7mm equals 1/4 do the math.
if you are cutting a round rod , just cut a ring untill you find the point of start. cutting a square rod just cut side by side (exhibit c... jury members)
once marked, lay the rod with the grove aligned with the edge of the table and press firmly and quickly on the ends, this willl snap it leaving a smoth clean cut. (not clean? ... deeper grooves next time) by the way, you can cut plexiglass like this, or even glass but ... nevermind.

Step 2: Making Holes

step two.
measure your rod, find the middle and distibute the leds as you like (this is reallly important, i mean to do it as you like, to fit your project size )
mine are like this (exhibit d)
once you have the locations use a felt marker and .... mark !

i drilled the end holes in the center of the rod, the rest i drilled in an angle 45º to 30º , we want the light beam to bounce inside the rod ( exhibit e.. your honor)

as you can see in the picture i made a previous one clear and holes in 90º angle (not good)
leds are 5mm in diameter , use a bigger drill bit so air can get out of the hole, 7mm , more is ok but less acurate, do not use less or else , the air buble will get inside and reduce brightness.

Step 3: Elbow Grease...

once you have the holes in place, get sand paper, the coarser the better
we want to kill the shine, make it translucent by sanding (i tried solvents , but no good)
sand untill you can´t see no more thru it.
i used a wet sand paper, you can use anything you have at hand even a file or the edge of a cutter blade will do!
remove all dust (or water in my case), make sure the holes are clean, blow air inside the holes to dry them, use mouth, pressured air, hair blower, time, sun ... but get the inside of the holes bone dry .

Step 4: Glues Is My Friend, Not My Enemy...

before you proceed ... test the leds one by one ... better to replace one than having a dead one inside the light bar.

look at the leds , they have a shorter leg , black goes here (negative - ) from the end take 5mm and bend it in an L shape, this will prevent any mistake when placing them in the correct (polarity) order

mix the glue carefull not to make many air bubbles (if you are using more than 8 leds make it in two parts, before u know it , glue is solid)

put a small drop of glue (not bigger than the led itself) inside the first hole and insert the led
CLOSE TO ONE SIDE, THEN MOVE IT TO THE CENTER . this will force the air out and place the glue around the led, if it leaks outside is ok (remember small drops but big enough to fill the gap between the led and walls ) repeat on each hole... aligning the legs properly .

if you get a leak of glue... DO NOT CLEAN IT RIGHT AWAY !!!
wait untill the glues starts to gel, it feels like a gumy bear, then you can cut it or scrap it, it will have "body" but is not yet fixed to the surface
leave a little of glue unused, this will be your reference of curing.

Step 5: Take the Spoon And...

get the key lime pie (home made, instructable cooking up!)
eat it while the glue gels completly ...
im serious, if you rush it , it wont stick.

have no key lime pie??!?!?!
take 10 min.
watch the tv. go to the restroom. go !

Step 6: Wiring ...

get the usb cable... i got mine from an old printer. you can get yours from ... thirft shop? friend?
as long as you GET IT CHEAP OR EVEN BETTER FREE! lol in this times usb cables are everywhere, don´t they?

cut the square part, NOT THE FLAT CONNECTOR
then (carefully) cut the plastic without cutting cables inside (cut like 3 cm/1" from the end)

remove static shield and mesh, not good for us, twist foil and mesh and cut.

identify colors (exhibit x)
cut green and white in uneven lenghts to prevent shortcut no ned to insulate, but be my guest .

connect leds as shown, use red and black !!! or two different colors.
best way for me was cut to distance between leds + room for peeled tip, peel tip, attach to led, then continue to next led

DO NOT SOLDER YET wait untill you have all connections, test it ! works ?...

now you can solder all, in one continuous movement , i think is better !
cut led legs as much as you want .

place double sided tape to fix usb cable in place...
test again! works?
cover cables side with masking tape/duct tape/etc to hold cables in place.

if lights are not working :

check polarity on usb source
check leds polarity
is it on ?
fix then ...

Step 7: Setting in Place...

now turn light bar on one side , leaving cables on the back, put on double side tape and fix in place.
final exhibit your honor...
hide switch, connect to usb, turn on ... and enjoy .

disclaimer...

do not try this at home ... go to a neighbor´s home.

im asumming you have some skills like:

basic electronic knowledge
drilling
soldering
using sharp objects
using epoxic adhesives

you are doing this under your own supervision! if you blow your computer, cut a finger, end up eating glue.. ... get the point?

i´m not an english "native" speaker, grammar and typos will be corrected on request.

comments and ways to improve are welcome.
acid comments will be ignored properly.

support your local key lime pie manufacturer