Terminal
Individual terminal pins for my internal connectors are Amphenol Deutsch-type pins. It turns out the 14-18 gauge sized pin fits well inside Lego hollow studs. The wide locking ring portion of the pin, seen between the two Lego halves here, is 3.3mm wide, and will not fit through a hollow stud. It just so happens that it will sit nicely between two of the 1x2 round end plates, or above a 1x1 round plate and below a 1x2 round end plate. It will not fit between two 1x1 round plates due to a subtle difference in the internal structure of the two pieces.. Between that and some cut pneumatic tubing, the pins are well secured and easy to connect to each other.
Terminal
Individual terminal pins for my internal connectors are Amphenol Deutsch-type pins. It turns out the 14-18 gauge sized pin fits well inside Lego hollow studs. The wide locking ring portion of the pin, seen between the two Lego halves here, is 3.3mm wide, and will not fit through a hollow stud. It just so happens that it will sit nicely between two of the 1x2 round end plates, or above a 1x1 round plate and below a 1x2 round end plate. It will not fit between two 1x1 round plates due to a subtle difference in the internal structure of the two pieces.. Between that and some cut pneumatic tubing, the pins are well secured and easy to connect to each other.