This toolkit shares insights and strategies from our 2021 pilot Open Problem Workshop series. We asked how might we help rethink how real world problems call for the expertise of PhDs from all fields? For those interested in hosting a cross-disciplinary workshop, we have assembled a toolkit of nine activities and suggestions on how to facilitate those activities in an online, collaborative setting. We uncovered three core insights and five guideposts for building successful cross-disciplinary workshops. We believe that openness requires us to empower other communities to replicate, fork, and remix our insights. *Authors listed are in alphabetical order to denote equal co-authorship.