Agnes is a little, vivacious dog from Ukraine. Unfortunately, she is seriously ill. Agnes suffers from polyneuropathy - she can’t move on her own. Animal foundation „Węgielek” decided to help the dog and asked student organization „Biokreatywni” from Silesian Institute of Technology to design a special wheelchair in order to give her a happy, healthy and active life. I became a person responsible for designing and constructing it.

There are many dog wheelchairs available on the market. Unfortunately most of them are made for dogs with weak hind legs and are no use to Agnes.

This is my first instructable. Unfortunately I decided to write everything down after creating the final version of the wheelchair so I don't have any 'in progress' pictures. I'll try to explain everything as clearly as possible.

Step 1: Materials

My dog wheelchair has a very simple design. Materials used to create it:

- 5 aluminium pipes, 25 mm outside diameter,

- 4 aluminium pipes, 12 mm outside diameter,

- 4 wheels (two of them are swivel)

- various screws, nuts, pads, rubber caps,

- 4 aluminium clamps,

- 8 plastic buckles,

- material for special harness.

The picture shows some of the crucial elements and tools used to create the wheelchair.

Additionally, I designed special mountings which were 3D printed. They will be described more fully further. I also needed some sewing materials, like straight pins, a pair of scissors or a sewing machine.
Agnes is quite a big dog (12 kg), so I decided to use a little larger wheels (200 mm diameter). They were taken from a used baby stroller.

Step 2: Prototype

The first step was to create a prototype. A first construction appeared to be pretty bad – the wheelchair was too shaky and couldn’t stabilize Agnes in required level.

The next idea was to suspend Agnes in the air with the use of special frame and harness. To build a prototype I used pvc pipes.

Step 3: 3D Model

3D printed parts were designed and exported to .STL. Unfortunately I don’t have a 3D printer so I sent the files to a 3D printing service where I got them printed using fused deposition modeling.

It was important to precisely measure the dog in order to make the wheelchair comfortable. I had to calculate the dog’s body width, body length and the length of the legs.

Step 4: Frame

The frame was created with aluminium pipes and ABS mountings. In the beginning I shortened all pipes to suitable length with a saw. The next step was to mark all the places where I needed to drill holes. The last move was to grind all sharp edges with a metal file.

In order to obtain a better visual effect pipes were painted with black lacquer.

Pipe locks were 3D printed. They consist of two parts glued together. Inside them I put previously polished rivets.

Inside swivel wheel mounts I placed bearings for easier rotation.

Stiffening bars were made with 12 mm aluminium pipes. In all of them I drilled two holes for small screws. The outer edges of the pipes were covered with plastic cosmetic caps.

Step 5: Harness

The harness was made with the use of two materials – hollow grid mesh from the inside and light, cotton fabric from the outside. Central part of the harness was strenghtened with EVA foam.

Step 6: Finish

The wheelchair allows an easy fit to the dog. The harness is mounted to the frame with the use of aluminium clamps clasped to pipes.

The result is a simple, lightweight dog wheelchair that can be easily used and adjusted. I hope it will improve the life of Agnes and allow her to move on her own.

Feel free to ask questions for more details.