You can find all necessary to print or laser cut your board and pieces on github. There are as well a set of the basic rules. With time we have found that the game is best played in scenarios, and those are to be set up by the master.
Is fairly simple to explain the rules, takes a round of game to start playing and it is quite fun.
We have as well a Telegram group for masters and wanna be masters here, that can be freely joined at this link https://t.me/legrandjeumaster