I built a homemade multitrack looper using Ableton and a custom Max4Live plugin. It works similar to a looper pedal, but (1) it gives you random access to all loops instead of just the top of the stack; and (2) it keeps every audio stream on its own channel, so you can route drums to a PA system, guitars to an amp, etc, instead of having everything go to a single output.

Here's some riffing I did on the Stairway to Heaven solo that showcases it: https://freerobby.wistia.com/medias/vcajgqerla