Here down below is several speaker box plan schematics from Fedora Audio. Hope this help you to create an ideal speaker for your events and projects!

Cubo 18 Inch Speaker Box

Full version schematics: Cubo 18 schematics speaker plans

Dynacord Speaker Box 18 Inch Long Throw

Full version schematics: Dynacord Long Throw Speaker 18

CBS Trilogy Speaker box 118

All of speaker plans schematics and measurement can be downloaded from Fedora Speaker Plans