Just sharing the process for prototyping and designing a target. The process for solving how to do things is enjoyable . We started with the request to come up with a crossbow discharge target by those that enjoyed our broadhead targets so we expanded from there. In order to speed up the process for the bag targets we built a compression box (compactor) making the process faster/easier and to make our targets more uniform and rectangular. We used to stuff the compressive material between the energy dissipation layers by hand but that was slow and not as tightly packed and was a hell of a workout.
As stated, this all started with the requested creation of a crossbow discharge target. Penetration tests due to the multi-layered energy dissipation layers were so promising we expanded to larger bag targets. Here are the early tests on discharge targets that are only 5 and 6 inches deep