Creating a crab pod was not so difficult. I used an old plastic case from heat shrink pipe that has dividers, so I simply cut out 2 segments off the side as one piece keeping the divider on the end like a mini case of it's own.

I cut down the front to make it sloping so it matched the angle of the lid when closed. The top simply has a corner piece of the plastic which slides in and out sideways. On the bottom you will see a hole cut out which matches up with the corner of the tank when in place, inside the pod opposite the entrance hole is 2 lines of silicone to segment off the corner about 3MM high.

The reason for this raised area is to put water into and the crabs food which requires water to expand, the crab will learn this is where food is and return here.

For the crab to get to the tank it needs a way up, I got myself a piece of bog wood from the pet store which is shaped with a large point and that just happens to be 11CM high. Perfect to just poke out the top of the water and lined up with the entrance to the crab pod gives him a way in.

I decided it was best to put the crab in the pod first and let him find his own way back into the water which he did 5 minutes later. Now he's up and down the wood using his pod all the time.

Using an old my old desk lamp which had 24 LEDs powered from USB I cut off a segment of 12 bulbs. I re-soldered the back so it was flat as possible then hot glued it all down and insulated. This was then UHU por glued to the top for a vibration resistant type mounting.

Now the original plate on top of the tank is solid white plastic. So I replicated the center piece out of perspex. Give it a good cleaning and then fitted it back in place. The perspex is 2MM and so is the white plastic so everything lines up nicely. Note how the lid goes under the crab pod meaning the crab can only exit via the hole in the bottom of his pod.

The water colour is a little brown tinted from the bog wood and this is natural and will take a few weeks to properly clear.

The final result however is excellent and I'm much happier with the tank design now.