This ist a small submarine I created.
I recommend printing the submarine at the highest possible resolution of your printer (for me it was 0.05 mm). Alternatively you can scale up the model a bit.
After you have printed the two Halfs two pins you need to glue them together. I recommend to only put glue inside the holes for the pegs. This is to prevent any glue from spilling out.
I've included a scad file so you can customize the label written on it.