After a recent illness limited the use of one of our ferret's hind legs, I decided it wasn't fair for him to have to lay around while the other ferrets got out to play. He wasn't able to get around and enjoy himself.

I decided to buy him a mobility aid, but after the sticker shock wore off (least I found was over US$300) I decided to make one. There wasn't much available online as far as DIY, but plenty of pictures of commercial models. I decided to make one myself, and this is the result, for around $30 in materials

Dedicated to Merlin, He went back home and got his wings back, 8/10/2009
He was one of those DMK ferrets rescued from a horrid breeder, and we gave him the best life we could for his entire stay with us. We miss you bud.

Step 1: Materials

Here is my bill of materials, approximate cost, and where I bought them. Store choices were based on convenience, and there are very likely better choices to be had. Just be sure you get the lightest weight stuff you can find that will serve the purpose.

$3 - 2 Clothes Line Wheels (Lowe's, Hardware, near nuts and bolts)
$5 - 3 foot perforated angle metal bar (Lowe's, Hardware, near nuts and bolts)
$6 - 500 Piece Plastic Wire Ties, aka Zip-Ties (WalMart, Automotive) - Won't use them all)
$3 - 6 piece wooden craft boards (WalMart, Craft Section)
$1 - Bandanna (WalMart, near purses and such)
$2 - Hook & Loop Tape, aka Velcro (WalMart, hardware)
$7 - Pair of Shin guards, soccer player type (WalMart, Sporting Goods)

(Lots of other stuff in the picture that I ended up not using. Your design may vary). If you look online, you may see why some of the extra stuff was bought but not used.

When shopping, keep in mind how long your animal's body is. You want a "cradle" that will support their body in a way fitting the injury. Sometimes you may want to support them by the legs or hips by means of a harness setup.

In our case, we needed to support Merlin's torso, because of an irritation with his legs that made us want to minimize contact there. If you need to support them by the legs or hips, you may want to use a different cradling method.

We chose the smallest shin guards we could find. You may want different materials depending on your particular needs. Be creative.

Step 2: Tools Needed

Hacksaw
File
Knife (Pocket knife, Utility Knife, or Precision (X-acto type), preference in that order)
Clippers, wire cutters, diagonal cutters, something along those lines for cutting zip-ties
Creative Mind (Very Important!!! Be sure it's not contaminated with toxic chemicals first)

Step 3: Cut Your Frame Rails

I cut 2 matching pieces of the perforated angle bar to roughly the same length as the shin guard (Cradle), and filed the corners and edges to ensure smooth edges without dangerous burrs.

This

Step 4: Attach Wheels

The next few steps are very subjective. This means you will have to tailor it to your own situation.
For me:
Attach the wheels to the frame rails by threading zip-ties through the frame surrounding the wheel and the holes in the frame rails.

It would be better to use one set of holes narrower than I show here. This will give you some adjustment to the balance point. I ended up going back and doing this on the final version.

Step 5: Make Floorboard

Take the craft boards, and cut one so that it is a bit shorter than the distance between the zip ties at each end of your wheel frames. Line it up between the rails and mark spots to drill holes in the board.

Use zip-ties through these holes to fasten it to the bottom of the frame rails on front and back of both sides. This is the basic cart. It should sit level, if not, adjust the wheels for a good balance.

Step 6: Attach Cradle

Attach the cradle to the frame rails by putting zip-ties through the ventilation holes in the harder shell section of the shin guards and then through the frame rails so that it was held securely. Be patient, it's tedious and frustrating, but your friend being able to get around is worth it.

Step 7: Add the Straps and Padding

We were able to use the strap that is part of the shin guard for one of the ones we needed.
I attached 2 strips of the "rough" part of the Velcro to each side of the "head" end of the cradle. You may need to do this differently depending on your animal.
I used one fairly short strip of the "soft" part of the Velcro to go over Merlin, just behind his front shoulders.

This helps him stay in the cradle. Be sure not to get it too tight. You may have to add a "chest strap" or even find a way to use a store-bought harness instead.

We used a bandanna to line the bottom of the cradle due to the nature of our ferrets problem. You may not need this, or may want to line and pad it differently.

Step 8: Bring in the Patient, Strap Him In, and Turn Him Loose

This is Merlin. This is Merlin with his new wheels (and his curious friend, Autumn)

The video is some of Merlin's first few steps. He's taken quite nicely to it, although he's still pretty weak, so he doesn't stay out for long. He still tries to use his hind legs, so we left them unsupported. If your animal is paralyzed or there is some other reason, you may want to cut the frame rails longer to give a place to support the legs, or even add extra casters (turn able wheels) up front or behind to support the extra weight.

Now he can get out and play with the rest of the family.