I’d like to identify the key elements in building up the moving robot arm to pick up Pingpon balls.

First he creates the base for robot arm by sending to https://www.3dfuel.com/ for 3D printing, he summarized tools/sources as below:

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Filament from: https://www.3dfuel.com/

Lulzbot 3D Printers: http://bit.ly/2Sj6nil

Lincoln Electric Welder: https://bit.ly/2Rqhqos

CNC Router: https://bit.ly/2QdsNjt

Ryobi Tools: http://bit.ly/2RhArcD

Axminster Micro Lathe: http://bit.ly/2Sj6eeN

3D Printer Filament: http://bit.ly/2PdcdUu

Soldering Iron: http://bit.ly/2DrNWDR

Vectric CNC Software: http://bit.ly/2zxpZqv

Equipped each arm part with servo, then installed Arduino UNO to program. Turn the math to move arms below into Arduino codes:

He referecen below open codes Arduino interpolation library to avoid writing from scratch.

Finally he rind sensors to sense if Pingpon ball is around.