I just built a Where's the Party At? sampler/looper. Since this is not as well known in the stompbox DIY community, I thought I'd introduce you guys to it and post a built report.
(thumbnails, click for full size)
This is an 8 bit looper, as the title says. So it sounds a bit crunchy, not like a regular pedal looper. It's not pristine. But if you set levels properly, it does actually sound pretty clean if you want it to. I have some clicking, but this has a lot to do with the way I routed my wires.
It does what no other DIY looper does: overdubbing, which alone makes it worth the price of admission. But it does so much more than any commercial looper does. You can record a loop, then automatically split it up into a variable number of slices, which get randomly shifted around. With large grain size, it just reorders your chords/melodic line. As the you go towards smaller grains, you get into glitchy, "clicks and cuts" territory.
It also does reverse and half time like most commercial loopers, and continuously variable sample rate, which changes playback or record speed and pitch. It has 2 separate banks, which can be independently edited without editing the other, and these 2 banks can be the same length or different lengths entirely. It actually has no facility for sync'ing the 2 banks, which might bug some people who are looking for a safer experience.
It lets you slice down the playback to just a certain window within the loop, and then continuously shift the window around. I made mine with an expression jack for the effects knob so I can shift the window around (and do all kinds of other fun stuff) with an exp. pedal. You can also vary the bit depth, down to 1 bit, which is very distorted and has no dynamics.
So you can use this as a fairly normal looper if that's what you want. I'd recommend tacking a 2-pole lowpass filter on the end to cut the aliasing, but you'd be good to go. But it really shines for people who are into weirdness.
Todd at narrat1ve no longer has kits of the first version, but since we here are manly men, we need no kits. He sells the bare boards and programmed microcontrollers on his site. The guy really knows his stuff. A version 2 of this will be coming out in the next few months apparently, which you may decide to wait for, but I'm not sure if that will be kit-only, or if he'll have boards.
Anyway, I recommend this project heartily. It's the only DIY project that does anything like this, and it's actually the only thing period that does some of what it does. It's not exactly as easy to build as a fuzz pedal, especially if you decide to do all the pots, switches, and LEDs offboard as I did (you'll have to do at least some of that to make it stompable), but not that difficult and hugely rewarding.