Just thought I'd share this one. 
I have been using a X Keys Foot switch  http://xkeys.com/XkeysFootPedals/index.php

I use it to Advance playlist/start and stop playback in Win Amp. It can be programmed to any keystroke. Including I have a saving for Sonar with W/R and spacebar. Cool. Hands free transport control. 
 
Anyhow it's 14 years old and started acting up. 5 years ago they sent me new mirco switches free! But now it's the hinge is binding so I find I'm stomping on it a few times to get it to work.
I almost ordered one for $129 but they punish Canadian customers with $80 shipping, (only $14 in the US) . plus they won't ship to my US depot which is less than a mile from me so I can deal with duty. I've e mail support to plead my case. 
 
In the mean time I looked at other offerings. 
I ordered a Cheapo double for $40 Can coming (free shipping) direct from China.  
https://www.amazon.ca/YobangSecurity-Customized-Control-Keyboard-Action/dp/B073GT43RH/ref=sr_1_15?ie=UTF8&qid=1520466665&sr=8-15&keywords=pc+usb+foot+switch+keyboard+pedal

 
It won't last but until I hear back from X Keys I needed something to get me by.
 
But then I stumbled on this and it has me very exited as this solves a few issues with USB foot switches. 
First it uses 5 switches, and it can use any foot switch with a 1/4" jack, something I already own, cheap to by and easily replace if it wares out. 
This also allows for custom placement of the foot switches on the already overcrowded floor around my mike stand. 
The box itself can be put at table height in my rack box.  
https://www.amazon.ca/StealthSwitch3-USB-Foot-Controller-Programmable/dp/B00NUFCR9Y

 
The reason I'm sharing is not only for live performers looking for hand free operation of anything you can imagine in a PC. ( or tablet)  but for in the studio controlling your DAW with your feet is handy for when you need your hands on your instrument. 
The sky is the limit on how you can program these foot switches to do any keystroke or even mouse clicks. It's a little pricey compared to others but it would seem it would last forever or until an unsupported OS came along. 
 
I use Win Amp for playback and 3 switches has been mostly all I need. But with 5 I could say add volume up and down or Playlist back one song and Pause. 
 
 
 
 
 
 
 

I've wondered abut using this as a footswitch
 

16 is a bit much, and getting your toe t the right one would be tricky.
 
However, cutting these int hemispheres you could stick them alternating to top and bottom rows.

 
 

Bit pricey.
 
https://xtempozone.com/

tunedeaf
Bit pricey.
 
https://xtempozone.com/

 
If it was hardwired I might pay that much. It looks well made. I could find a use for the extra pedals like controlling my Blackstar Amp software. 
Blue tooth is a PITA as everything I own that uses it always takes a few tries to pair it up. It never seems to be stable.  I see it comes with software which is important and it is made in the USA like the X Keys. . 
Most of the Chinese foot switches have super funky software that you download and it's like it was written for XP so it just barley works. You program the foot switch and it has a static memory and you only do this once and it will always send the same keystroke, even when hooked to a different computer. 

After several years, I still see that the only affordable multi-purpose foot controller is FCB1010...
 

I’ve been using the Stealth Switch for years now, great product! I have a couple of heavy duty pedals (usually used for keyboard sustain, etc.) that I use to flip pages in my PDF lyrics binder when we play out.

Here's the link to Amazon US: https://www.amazon.com/StealthSwitch3-USB-Foot-Controller-Programmable/dp/B00NUFCR9Y/
 
Current price is US$74.85. That's a LOT less.
 
Saved to wishlist. Thanks for sleuthing and sharing!

TheMaartian
Here's the link to Amazon US: https://www.amazon.com/StealthSwitch3-USB-Foot-Controller-Programmable/dp/B00NUFCR9Y/
 
Current price is US$74.85. That's a LOT less.
 
Saved to wishlist. Thanks for sleuthing and sharing!

 
Wow, That's a way better deal.. Going to order that now. 
 
Done,, $80.72  free shipping. 
Now I'll look into buying a few more foot pedals. I have 2 very old Roland pedals. 

Just a follow up on this. 
I ended up ordering way too many foot switches,, but I've kind of put them all to use for Live performance and in the Studio.
 
First the BIG YELLOW dual USB  came direct from China. It uses the same software which has now been updated for many of the cheap Chinese foot-switches. Same as the 3 pedal one behind it. 
Was easy to program it and the assignments stay with the pedal so you can move it to any computer and it will stay the same. I have assigned "R" and "SPACEBAR" and use it for hands free recording in Sonar. Highly recommend this one. Very solid,cheap, works. 
 
I then received the Stealth and it was surprisingly small! And the jacks are all 1/8" not 1/4". My fault , didn't read the fine print. I have a few Roland sustain/drum machine pedals and I ordered 3 more 1/4" based pedals. Those I'm now using to toggle my Lexicon and Mixers effects off so I can take between songs. I use the Lexicon for general reverb/delay and the mixer only for special long delay. 
I had to order the proper foot pedals from Stealth and now have those. I only bought 4. A fifth I guess would be Pause.  
 
You can see it's getting pretty crowded down there,, and I also have a few Stomp boxes not shown! The Big Yellow is not used live, I just put it there to take the picture. 
 
 
 
 
 

Looking at your picture, I have remembered an instrument which can be played by foot... and:

A bit pricey, but I guess the quality should be good. 17 velocity sensitive pedals in one package