The point is ouija boards remain unpredictable.
Poeple can use them as a tool intent on evoking nasty stuff and get zip apart form serious ribbing from associates who watched them fail.
Others can go play with them thinking they are but a toy and find their lives get tipped upside down by an entity that decides to turn up.
It does not matter if such a board is home made or shop bought or bespoke to order. It is also mistake to think entities play by human rules.
It is for these reasons the bible warns sternly against seeting out on a dangerous sea in a little dingy and thinking you will be fine.