Interesting, it looks like their oxidizer is nitrous oxide, but I can't tell what their solid fuel is. Common hybrid solid fuels are not described as "resin". It is possible they are using HTPB. We can see they have at least two other casing/nozzle ready and have students design some part of the casing, which indicates that this club have access to a machine shop or have enough funding to get these things machined. Unfortunately it seems that they cheapened out on the test stand. A well design test stand should not have allowed the engine to come off the stand like a boomerang. It looks like a blowback failure or a burn through which could have killed someone if they got unlucky.