Disclaimer: I don't sell any of the products mentioned below, and have no connection with any manufacturers or retailers. I only use some of the products, in my own unpolished way.

For solo guitarists, adding some percussion to your act is difficult at best. Some people might be able to play guitar with one hand, but that's way out of my league. If you have at least one vocalist (not encumbered with a guitar or other instrument) with you, you might be able to have them do additional duty as a tambourine operator, but otherwise, the beat will probably come from tapping your foot or feet. Even for duets or trios who don't have a drummer, a "stompbox" can let you be your own drummer. A stompbox (not to be confused with various effects pedals that are often called stompboxes) is usually an empty metal or wooden box with a guitar pickup or microphone inside. When "stomped" or tapped with a foot, the sound can be amplified and produce a kick drum (bass drum) sound for rhythm as you play.
We probably all know at least one drummer joke, and I'm certainly not picking on drummers here, but many times "there's never one around when you need one." A stompbox will always be in time with you, and you won't have to buy it beer, pizza, etc.

The following is from my rudimentary knowledge of stompboxes, much of which I gleaned while Googling around for more information
There are two basic types of stompboxes, active and passive. Active boxes require a power source, usually a 9 volt battery. There are also some boxes, more like an effect pedal, that produce a sampled sound or combination of sounds when triggered by a pad on the box (e.g. the Cajokick, which can be played with foot or fingers) or a stompbox connected to the pedal. The converters require a battery or external power supply.
If you watch any of the online videos demonstrating various 'boxes, it's best to use headphones, unless your computer has a good sound system attached, including a subwoofer. If you're playing with a stompbox, it might also be a good idea to run the 'box through a bass amp or subwoofer for better bass effect.
The first stompbox I acquired was an SX SBX II from Rondo Music. The SBX is an active 'box, and uses a 9V battery.

My next purchase was a Footbass. The Footbass is in a metal box, doesn't require a power source, and has two output jacks. The builder says that's in case one jack fails, but the box is pretty solidly built, so I might use one output to trigger my Finhol™ Stompcon™.
Finhol is a German manufacturer of musical instruments and accessories. I found a good deal on an SC-01 Stompcon from a U.S. retailer, and decided to try it. This is the SC-01:

My testing of it so far shows that it will work with the SBX II or the Footbass. I've only briefly tried it into my Roland Micro Cube amp (5" speaker), and the 12 different sounds it produces seemed pretty realistic.
Recently the Finhol Cajokick showed up from a vendor on eBay. The Cajokick produces some different sounds from those made by the Stompcon. (Cajon Bass, Bass Drum, Synth Bass, Hi-hat, Ride, Rimshot, Cowbell, Tambourine, Cabasa, Handclap, Clave and Guiro.) The Cajokick can be used on the floor, and tapped with the foot, or attached to the side of a cajon and played by hand.
Schlagwerk is another German company, making cajons and other percussion instruments. They also make a Cajokick, which looks virtually identical to the Finhol. I haven't tried either one yet, but I'm tempted to get one some day. (I have an LP cajon.) The Schlagwerk CKICK1 is available on Amazon and at Musician's Friend.
The only box (pedal) I've seen so far that can produce more than one sound per trigger is the Finhol Auto Stomp™ Player. I think it can be switched into an automatic mode and have tempo (50-200 BPM) set by tapping the stompbox that triggers it. List price on the ASPB-01, which includes a Kick Box Basic to trigger it, is $649.99; without the Kick Box, $579.99. The U.S. distributor is Big Bang Distribution in Northridge, CA.
Among the numerous brands of stompboxes are two made in Australia, the Peterman Puck'N Stompa and the Wazinator. This video of Juzzie Smith using a Wazinator led me to buy a couple of his CDs, tune an old electric guitar (with a rather high action) into Open E, and start thinking about learning to play "cross harp" sme day. (In another video, he explains how he's playing an A harmonica in E for that song.)
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