I found this earlier, it seems pretty simple
(https://content.instructables.com/ORIG/FMA/BLWS/L0856F1P/FMABLWSL0856F1P.jpg?auto=webp&frame=1&width=933&height=1024&fit=bounds&md=b3f27b057c9e6c0ceb6848e20bc3e946)
https://www.instructables.com/Bluetooth-DCC-Command-Station/ (https://www.instructables.com/Bluetooth-DCC-Command-Station/)
PCBs and case etc are available through here
https://www.facebook.com/groups/290750671312687/posts/2002562943464776/?comment_id=2006042199783517&reply_comment_id=2006930159694721¬if_id=1651597173190822¬if_t=group_comment_mention (https://www.facebook.com/groups/290750671312687/posts/2002562943464776/?comment_id=2006042199783517&reply_comment_id=2006930159694721¬if_id=1651597173190822¬if_t=group_comment_mention)