Poseidon is my first shower wheelchair design. My goal is to make a wheelchair that is more functional and substantially less expensive than the plastic shower chairs currently available. 

I am using inexpensive industrial style plate casters so they can be replaced as needed. The front wheels are 4". The anti-tipping wheel is 3". The rear wheels are solid to avoid the need to periodically pump them up. The axle receivers are made from 1.25" square Zinc tubing. As a result, the quick release axle will not rust into the axle receiver since the contact space is relatively minimal.

The right armrest is extended forward to provide a handle for transfers. The left armrest is positioned back in order to provide an open space for transfers. A sliding board could be placed in this area.

Poseidon features wheel-locks with extended handles to make it easier to lock the wheels with wet hands.

NOTE: For my prototype I am using standard T-brackets that are cut to create a DIY Slip-T bracket. An actual Slip-T bracket is preferable. I did not have any on hand. I have to order them online. Standard T-brackets are readily available at local hardware stores and are also less expensive.