Secure Battery Pack
Use two M3 x 5mm flat head machine screws to secure the 3xAA battery to the 3D printed battery mount. Orient the battery holder and place over the standoffs. Line up the mounting holes. Insert and fasten two M3 x 5mm flat head machine screws through the built-in standoffs.
Secured Battery Holder
The machine screws need to flush with the battery holder in order to properly fit the batteries. The power cable passes through a cutaway in the lip.
Snap Fit Case
The battery mount features a lip with indentations that snap fit and lock onto the case. The case features nubs that are press fitted into the indentations in the battery mount. Using this design method the case can be securely shut but still be reopened. Moderate effort required top reopen, suggest using a finger nail or spudger prying tool.
You can choose which LEGO® compatible plate to install onto the case. The under side of bricks are the tubes and the top side are the logic studs. The bottom of these parts are both flat and can be glued to the battery mount or case. You can use superglue to permanently bond two surfaces together.
Secure Covers to Case
Apply glue to either side of the case or battery mount first. The bottom of the case has a border that can be used to apply superglue. The bottom of the battery mount has more surface area to work with. A fine tipped nozzle and squeeze bottle is nice for making precision glue application.