At this point if REAPER and the Halloween Noise Maker program are working, BACK UP YOUR ENTIRE SD CARD to another computer!  I used the excellent "Win32 Disk Imager" program found at:  https://sourceforge.net/projects/win32diskimager/

Since you have a working backup of your working installation, you can do a "sudo apt-get update" and "sudo apt-get upgrade" to update your OS.  Fingers crossed that your REAPER and Halloween Noise Maker program still function without issues afterwards.

You'll want the pi to start REAPER automatically after power is applied to your Pi. 

1)  Save the project file "startreaper.sh" in your Pi's home folder.  If you didn't change your user name on your Pi, this would be the /home/pi/ folder.  This script basically changes to the directory where the Windows reaper.exe file sits on your SD card and executes that file using the Wine program.  Inspect the startreaper.sh script with a text editor to make sure the path to your reaper.exe is correct.

For good measure (may not be required?), I made that startreaper.sh script file executable in Terminal with:  "chmod +x startreaper.sh".

2)  Save the project file "autostartreaper.desktop" into your /home/yourusername/.config/autostart/ folder.  Inspect the contents of that file with a text editor to ensure that "Exec=" line accurately reflects the path to your startreaper.sh file in your home directory.

This is a bonus step but makes things work much better.  If you pull power to your Pi, you risk scrambling your OS files.  In addition, REAPER may pop up a dialog box the next time the Pi boots saying that the Halloween Noise Maker program didn't load properly.  In that case, it would wait for a "Yes" or "Enter" key input before starting the noise making, which would be an issue for a headless system.  The Pi would boot, but you'd hear no sound.

The way around this is to install a push button connected to a GPIO pin (I chose GPIO 23) and a ground pin (I chose the ground pin right next to GPIO 23).  Then you install software that automatically issues commands for a safe shutdown of the Pi when the button is pushed.  This would be handy for ANY Pi project.

I won't recreate the wheel here, so just watch this video.  The video poster's file site is:  https://github.com/km4ack  

This is actually the easiest step.  I found an 8-track tape storage box at a local Goodwill for a few dollars.  I bought a USB mic from MicroCenter Mall on sale for $16.  I cut a hole for the mic with a doorknob hole cutting bit and also cut a square opening in the back of the drawer so that cables had room when the drawer was opened.  I wanted to be able to hook up either powered computer speakers (1/8" jacks) or guitar amps (1/4" jacks) to the box so I cut holes in the back for both to be hot melt glued in.

I purchased a 1/8" male to two 1/8" male splitter cable.  I attached a 1/8" female - female adapter to one of the splitter leads to serve as the 1/8" box output port.  The other splitter cable 1/8" male lead was plugged into another 1/8" female-female adapter, and I plugged a 1/8" male to 1/4" female adapter into that.  The 1/4" female port was the box output port for guitar amps.  (see pics).  All was ordered from Amazon. 

I mounted any cheap noise making toys or items I found at my local Goodwill for just a few dollars.  I think the high pitched triangle and similar items work exceptionally well with the Valhalla plugin effects, but each item added it's own special flare.  As you can hear from the videos, the special effects plugins give an eerie "Halloweeny" sound even when nothing is being played on the box.

The kids that played with it were amazed and enjoyed it immensely.  Thank you, Hackaday, Kristina Panos, and all the original project posters for the inspiration for this fun project!!