try mybinder.org
mybinder.org can be pointed to a repository containing notebook files, and instructions to install the necessary dependencies. Then it builds a Docker image, and can launch an individual jupyter server using that image for anyone clicking a link. That could be a better alternative to spot-sandbox, especially for teaching. It would also allow easier experimenting with code on different branches.
As a first step, let's just figure out how to configure mybinder.org to run Spot.