need help finding the rihgt snsor

Inductive technology won't help you much, that's typically for sensing metal, so you'd need metal balls, also you'd need a ton of sensors.  Honestly I would look at using a plexiglass table and use use a webcam and a pc underneath.  If you put LED's in the side of the plexiglass, you can use frustrated total internal reflection

http://www.cs.ucf.edu/courses/cap6105/fall2010/readings/Multi-TouchInterface_FTIR.pdf

That's quite ironic I was looking at FTIR videos on youtube seeing if they could work I figured I would have to have 2 projectors and 2 webcams 1 on each side then I could make a program for a raspberry pie or some really cheap computer and hook everything up to it. thank you so much for telling me about inductive because I had no clue what it was telling me no matter how much I looked at it. do you think I could use something cheaper than plexiglass since it is a little expensive or I might be thinking of the wrong thing but I was thinking of acrylic for the glass. thank you for answering though and I'm still open to any other ideas if anyone has any any. the one thing that I am looking for is a one touch system that can or may be programmed through an arduion board.

You could do one camera I think, maybe wide angle lens if you have to, or webcams are cheap enough, 2 wouldn't be hard.  Yeah for lighting, you'd need something like a projector.  The application is very much like a touch sensitive table, except you don't care about fingers.

Alternatively, you could use a webcam high over the table and a projector high over the table as well.

Or for sensing you could use IR emitter/detector pairs and you get kind of a matrix effect, but then it sense indifferent to what is blocking the light.  A lot of industrial touchscreen use this techonology, or even acoustic.  I have 2 32" touchscreen monitors that use surface acoustic.  If you used the IR pairs, you could then have your lighting under the table without need of an industrial controller. 

would there be 1-2 IRs or would i have to get a few spread throughout the table im looking to see if i could make it to were it could be moved in as little as few as steps as possible so the FTIR would be a last but reliable source. the IR system sounds promising though. i will have to look into those. thank you.

In neither case you'd be using 1-2.  You'd have however many you need in the x direction and y direction for your resolution.  Its the similar for FTIR, except you wouldn't need receivers in that case.  Think of it this way, the IR pair would create a line across the surface.  You'd have lines going in the x and lines going in the y.  Every pair is one line.  When something is placed on the table, it will block an amount of x and y lines, that will give you a position of the object (just take the center of each of the blocked sets).  To minimize the amount of pairs, you'd have to increase the object being sensed, so you could raise the pairs up a bit to the half-way height of the ball and then you will need as many pairs in the x direction (with of table/diameter of ball + safety margin) and y direction (length of table/diameter of ball + safety margin).  The safety margin is because you don't want the width/diameter exactly, you want to throw a few more evenly spaced pairs in there to guarantee that the ball can't be in between lines (which have small widths).  Alternatively you could go below the table, but then it more complicated.  You'd have to have the transmitter/receiver next to each other and measure reflected light, all of which would be affected by overhead lights, the lights coming up from the table, and then you'd have to do your calculation based on the area of the table and the area of the ball that is visible, because its possible the IR pairs are only good for a short distance above the table and not the half-height of the ball, to ensure that a ball can't land between sensors.

Keep in mind you will be using a lot of IR pairs and a lot of LED's, so this won't be cheap and it won't be easy.  You won't get away with just a single Arduino to control your hundreds of lights, you will need controller cards, you will also need to be controlling and reading the IR pairs, etc.

Sorry I have not gotten back with you I have had a busy weekend. I was thinking I think my final decision is to have 2 projectors and 2 cameras for a FTIR system. Have one on each side of the table and have them hooked up to a computer or pi devise. I'm trying to design a way to hook the camera and projector up so that they are running off the same power and usb cords this will be beneficial in 2 ways. One it will save space and precious ports for whatever comp. I'm using and 2 I would like to have them set up in a way that they could be lifted up and down inside the table for easy transportation and to be able to have the whole table visible.

to say everything that I want to do is this:

have the paper on the glass

the camera/projector setup ( both be connected to each other with a rod to ensure stabilization) each set on rod to be lowered and raised to make a second layer

then when the wood from the sides gets locked into place that will secure the camera/projector in place from moving

the hardest thing I think I will have to do is to setup a program to where it will be an animated background or a still one( easily switch theme if wanted) and when you click on a spot something will happen

I'm not sure if I have said this before but I am also having an automated/manual scoreboard which will be tied into the program I think and a light up net already have the net figured out

this is my final design as of right now but if anybody has any other methods they would like to throw at me I'm all ears but this is very customisable and somewhat feasible and somewhat the easiest method I have to date

the net will be set to its own arduino board separate from total system.

I have added a picture of the notes that I have been taking on the system if they make more sence.

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