Some people have tossed around the idea of making Trinitarian friendly Sunday school material.

Does anyone know of any that are Trinitarian in focus?

Usually, I take what's at hand and tweak it a little to make it Trinitarian. I've found that most of what conventional churches have needs only a little tweaking. It was not necessary to reinvent the wheel even if it was something really Modern and quite wrong about who God is. I once had to use materials by a very well known Christian speaker and he said things like God was silent in the 400 years between the OT and the NT and he emphasized how separated we are from God. That took some major tweaking.