I was a little bored and was looking to do some dope changes in my 505, I was like what I can do with this machine?? maybe some paint? nah... a custom skin??... couldn't find any... so then I thought about hey! could be cool if I can do something with the display... since the original display it is so boring (the color scheme it is not that great...) so I was doing my research and I found this shit called polarizing film used to invert the LCD displays... so I said yeah!!... I bought a polarizing film sheet from American Science & Surplus I paid like $2.5 for a 12" x 7 1/8" sheet + S&H.
So...
to the tutorial...
***WARNING!! DISCONNECT THE POWER SOURCE BEFORE YOU PROCEED!!***
First thing to do is remove the knobs and data wheel, please see pic below:
Turn down your SP and remove the screws and SM cover, see pic:
Be careful pulling apart the top and bottom part of your SP since both are connected through some ribbon cables and you could damage the cables if you are not careful enough.
Then you need to take out your screen removing the 4 screws that hold the screen to the case
When you have your screen removed you are going to find that it has a polarizing film in it so you need to remove the old one using a sharp knife and being very careful, TIP: you can start with one of the corners as you can see in the pic below, then you can pull the corner and take out the film, be patient and do this very carefully... applying to much force can ruin your display!!
Take your time to remove the film, anyways it is a very small piece and its going to take not that long, but take your time!!
Then after remove the film, clean the display using some LCD cleaner, be very careful doing this too and make sure to remove all the residues of the previous film in there, it going to give you better results if you clean it very well!
Then place you new polarizing film on top of your display (I turned on my SP just to show you guys how this shit looks but with the SP turned off you also going to notice that the display turns completely black!)
Play with your film until you get to the point were your screen it is the darkest.
Then cut your film in the angle that you find that it invert your display... using some tape (take your time to do a clean job!) make sure you put the film the right way and then you can start the reverse process to close your SP, first installing your screen back, then the top and bottom part of your SP, plug it in and turn it on!!
This is very easy! you just need to have some patient and some tools (Phillips screw driver, a sharp knife, LCD cleaner, tape and your polarizing film) so if you are willing to try, then give it a try! this are some screen shots so you can have an idea!!
Good luck and enjoy your new MOD SP-505!!
thinking about inverting mine too 
