Sorting machine, N00b needs help :)

Hi all, I am new to this forum and not an engineer so I will need all the help I can get.
Anyway my goal is to create a sorting machine, I will be outsourcing but need to get my concept right and just get more feedback.

you can find my very basic concept mocked up here: (see attached pdf) or here:

[ATTACH=CONFIG]1109[/ATTACH]

or pdf version [FONT=Verdana][ATTACH]1108[/ATTACH][/FONT]

Anyway what it is, is a sorting machine. so imagine the machine sorting assorted lego pieces (150mm~3mm in [FONT=Verdana]diameter)[/FONT] by colour and/or weight. I am aiming for it to be a compact design that fits on a desk with 4 output collection bins.

Step 1 - Set criteria to sort from controller, eg colour / weight ;cool;

Step 2 - place assorted blocks in ;cool;

Step 3 - pieces
;?(this part I mainly need help with, my system in the image has 2 rubber / foam wheels that pick up the pieces and then drop them one at a time with a trip IR or laser or something like that detects as the piece falls and stops the wheels moving untill analysis is complete.)

Step 4 - Isolated piece is [FONT=Verdana]analysed[/FONT] for weight and colour
;?(this part need help with because colour sensors from my [FONT=Verdana]knowledge[/FONT] are limited to close proximity from my understanding, so if pieces are from 150mm~2mm in [FONT=Verdana]diameter[/FONT], how would the colour sensor target the object.)

Step 5 - Pieces are pushed off analysis plate into one of 4 bins depending on [FONT=Verdana]inputted[/FONT] criteria.
;?(Not sure if my push plate method is the most effective or if there is a better method.)

Thanks so much everyone in advanced for input, it will be greatly appreciated.