Soft-sided carriers are light weight and great for short trips around town, like trips to the vet. Most of them have generous amounts of pocket space for carrying travel essentials, like vaccination records, harness and leash, small containers of food and water, etc. The downside is a lack of sanitary facilities and no mounting places for food dishes and water bottles, so they aren't very good for longer trips.
Nowadays there seem to be a number of affordable soft-sided carriers on the market, but such was not the case a few years ago. Making one was my first project, aside from making litterboxes out of Rubbermaid dish pans. The total cost was around $40-50, which is still slightly cheaper than most of the commercial offerings.
Materials and tools
Begin with the largest sports duffel bag you can find with mesh pockets on the side and on one end. The pictured duffel is 27" x 12" x 13" and cost around $30-40 at K-Mart.
Next you will need to stop by the hardware store and pick up materials to make a bracing frame to fit inside the bag and keep it from collapsing. You'll need about 15' of 1/2" PVC pipe (three 5' lengths), two 10-packs of 1/2" PVC tee fittings, and a 10-pack of 1/2" 90° elbow fittings. This should cost a little under $10.
While you're at the hardware store, pick up a PVC pipe cutter (which looks like a C-Clamp with a small, round blade inside) and a utility knife, if you don't already have one. You could use a miter box and a shark-toothed saw instead of the pipe cutter, but I find the pipe cutter handier, and you will be able to use it on other projects found in these pages. Finally, a pair of scissors and a Sharpie permanent marker will also be useful.
Preparing the bag
I chose to open up only one of the mesh side pockets to use as a doorway. This cuts down on ventilation, but gives the ferret more privacy. (The carrier also makes a great nest box for use in your home.) The other side pocket is used for storage.
First use the utility knife and/or scissors to remove the backing behind the mesh. Be careful not to cut any of the stitching that holds the mesh in place, and be extra careful not to cut the mesh. A carpet shark will be quick to exploit even the smallest nick and enlarge it into an escape route.
Inside the bag, again use the utility knife and/or scissors to remove the inside wall of the pocket. Again use the stitching as a guide and be careful not to cut too close.
Finally, repeat the process with the large mesh pocket on the end, removing the lining behind the mesh and the inner wall of the pocket.
If you're truly concerned about ventilation, then go ahead and remove the lining and wall of the other pocket. The solid end pocket still provides plenty of storage. You might also be able to install some large grommets in the solid side of the bag (the side opposite the small pockets) and in the top cover.
Preparing the frame
The next step is to make an interior frame using the PVC pipe and fittings. Being my first project, it is possible that the pictured frame is a bit overbuilt, but it does the job. The frame should be large enough to fit snuggly inside the duffel, and may require some creativity to insert it through the top cover.
This frame uses 12 tee fittings and 8 elbows at the corners. PVC "corner" fittings (more formally known as "side outlet elbows") would have been easier to use, but are not stocked by most hardware stores. There are online sources, however, such as PVCFittings.com. (Link valid as of 2006.04.18. Search for "PVC side outlet" to find other sources.) A short length of pipe, about 1" long, is used to join the elbows to the tees at the corners.
Note that this frame is not glued. Since these pipes do not have to hold water under pressure, the pipes will insert tightly enough into the fittings to hold the frame together if you apply some force. I dislike using the PVC cleaner, primer, and cement if they are not really needed, because they are highly toxic. If you do decide to glue the frame, make sure that you do the job in a well-ventilated area, and do not expose your ferret to the frame until the cement has had plenty of time to cure and stop outgassing toxic fumes.
Completing the project
Now all that remains is to insert the framework into the duffel. I put a 17" x 24" incontinence underpad beneath the frame to help catch any "accidents". Add some blankets and a ferret, and you're good to go!
But, please, not to the vet, huh? [Fizzbin]
Applying the Fizzbin Test
Fizzbin inspects the workmanship and registers his approval.
However, he feels the view is better when you're riding on the outside.