Ximera is a free, open-source platform for converting LaTeX documents into interactive webpages. The resulting pages include autograded homework problems with scores that sync back to LMS gradebooks. Instructors can watch their students working in real-time. The basic principle of Ximera's design is to leverage existing standards and code, e.g., LaTeX as a source language, git for version control, GPG for authentication, JavaScript for interactive content, xAPI for logging learning events. While this basic principle has made the development of Ximera remarkably rapid, it also imposes a significant burden on users who have to install quite a bit of software to get started. CoCalc solves this problem: interested parties can quickly build a "xandbox" on CoCalc where they can author LaTeX files with the Ximera document class, learn the syntax by watching the effects on a PDF, and then deploy an HTML version to a Ximera server. This talk includes a demonstration of using CoCalc to provide "xandboxes" for Ximera. In the xandbox, we will use SageMath to produce some interactive content -- and point towards many opportunities for coding sprints.