One possible idea is to remove all the fabric from an old twin baby buggy, except for the canopy (hood). Leave that in place for rain protection. I'm now examining the stripped-down chassis to see what can be done. I'm considering attaching a 'hammock' of very strong material such as canvas (like those hammocks that one attaches across the back seat of a car to protect it from dog fur and/or wet paws), from the handle of the chassis to the metal bar at the footrest.
The canvas can be punched through with several strong metal grommets along the top, bottom, and sides. Then strong nylon rope can be fed through the eyes and the hammock can be securely attached with hooks to all four sides of the metal framework of the chassis, obviously in areas where the hooks don't slide down the metal tubing of the framework. The hammock shouldn't be too taut because it should 'belly' down enough to support a sturdy dog-carrier. Nylon rope with hooks attached can be threaded through the grommets and then attach a dog-carrier to sit securely on the hammock. I have started this process. I've stripped my twin baby buggy down to the chassis and hood, now I'm at the stage of trying to select one of my large pet carriers.
Safety is paramount with a home-made pet buggy. Depending on the shape of the chassis (if the metal frame has one or two horizontal crossbars in the right positions to support the weight of a pet-carrier), a possible option would be to "securely" and "safely" attach a strong, commercial pet-carrier directly to the stripped down chassis. I don't think the shape of the metal frame of the chassis I'm using lends itself to attaching a pet-carrier directly to the framework, so I'm probably going to have buy a piece of strong canvas that fits, but overlaps the framework. I will then glue down all the edges to get a tidy look, and buy one of those gadgets that can punch holes through canvas while simultaneously inserting metal grommets into the holes. Then I'm going to attach the canvas to the chassis and the carrier to the canvas.
In theory, this should work, and I should end up with a pet-carrier attached to a strong canvas on the very strong framework of a used baby buggy. It's worth a try because any pet buggy that has a chassis as strong as a baby's buggy would cost a fortune.
