First step is easy - go build the Arduino Laser Show with Full XY Control project: http://www.instructables.com/id/Arduino-Laser-Show-with-Full-XY-Control/ Step 31 details how to upgrade to a green laser. Then ...
You can get the updated Arduino code from this link: https://github.com/nothinglabs/lasershow/tree/master/lasertweet Download it - and then upload it to your Arduino. In addition to the code that supports ...
You'll need to install some software on your computer to run the scripts.
The exact process will vary somewhat depending on your OS.
If you haven't installed Python modules before - it might seem a bit intimidating at first. Just follow the instructions provided on the various sites below - and it should just be tedious - not difficult.
Tip for Windows users - when running Python - you may need to enter its full path - such as c:\python27\python
If you install everything listed below in order - you shouldn't run into any dependency issues.
You'll need to make a few minor tweaks to the code to get things working.
ser = serial.Serial('COM7', 9600)
Change the com port number to whichever your Arduino is on (you can check this from the Arduino software under the Tools menu)
For Mac / Linux this will look something more like "/dev/tty.usbserial-A700e1B5"
searchString = "INSTRUCTABLES"
You get the idea. This searches for any tweet with the specified characters (put a '#' before it if you just want hashtags proper).
tweetsToGet = 20
The number of tweets to fetch each loop.
filterRetweets = True
This tells the script to not display retweets (they can get spammy).