DIY Tidy Cats (TM) Breeze (TM) reusable pads

One of my vet school classmates converted me to the Tidy Cats Breeze litter box system about three years ago, and I kind of love it.  Cleaning the box is simple and quick, odors are minimal, and best of all, there's no clay litter to track all over the house.  The only thing I dislike about it is the price of the replacement pee pads--they're about $7/pack.  With 2 cats and 3 litter boxes, that costs me at least twice as much as a box of cheap clay litter every month.  So I decided to sew up some washable, reusable pee pads, using the superfluous internet resources available for DIY cloth diapers.  I'm posting this because, apparently, this is the one thing the internet didn't know.  I've described exactly the materials and methods I used, but feel free to adjust based on your own preferences and research. :)  Full disclosure: I'm a veterinarian, not a seamstress! Here's how mine turned out:

In the words of our beloved veterinary biochemistry professor, "Let's get staated!"

For 18 pee pads

Materials
Solid white cotton fleece 42" wide - 3 yards (topmost layer - the vet inside me wants to know if my cats ever have blood in their urine. I found some at Jo-Ann's for $2.49/yard near the baby fleece)

Zorb super absorbent cloth 45" wide - 3 yards (most absorbent layer)

Cotton fabric "bottom sandwich" (layer between PUL and Zorb - color and pattern don't matter.  I cut up an old holey black fleece blanket for this.)

Polyurethane laminate (PUL) 64" wide - 2 yards (waterproof backing)

Scissors or rotary cutters

Tailor's chalk or a Sharpie and a ballpoint pen

Sewing machine and thread (or you can sew by hand... it'll just take a lot longer!)

Straight pins

Yardstick, ruler, and/or measuring tape

Instructions

1. Measure and cut all your fabric
Measure the Zorb and whatever "bottom sandwich" layer you're using into 15 1/2" x 9 3/4" rectangles (these are the dimensions of the inside bottom of the Breeze tray).
Measure the PUL and white cotton into 17 1/2" x 11 3/4" rectangles (the Breeze tray is 1" deep all the way around).

I a disposable Breeze pad to act as a template for my bottom sandwich, since the fleece blanket I cut up was black and my Sharpie markings wouldn't show.  Like in the picture below, I used binder clips to hide the edges of the pad so the size was more accurate.  Still, the "template" cut method is a bad idea.  Measure whenever possible and your pads will fit perfectly into your Breeze tray without fuss. :)  I used a Sharpie for this, but tailor's chalk would've worked better.

I had to do a little math with the fabric widths to decide how best to get 18 rectangles out of the yardage I had.  Hot dog style or hamburger style?  With the 45"-wide Zorb, I ended up measuring the rectangles hamburger-style, as shown below.

Nice job measuring that Zorb! Now cut it up! 

This would've been so much faster with a rotary cutter.

Admire your perfect stack of Zorb.

Go ahead and measure and cut all four types of fabric.  Make sure you match up the right size rectangles to the right fabric!  White cotton and PUL are big, Zorb and bottom layer fabric are small.

From left to right: Zorb, white cotton, bottom sandwich, and PUL.
Lotte's favorite was the fleece blanket bottom sandwich.

2. Mark the Zorb for tri-folding
You may think you don't need your cat pads to tri-fold, but this is just my practical way of attaching the Zorb to the bottom of the sandwich.  Plus, it makes it easier to remove the pee pads from the Breeze tray when they're full.  I used a Sharpie for this, but tailor's chalk would've been better.

Use the ruler to mark at 5" and 10 1/4"... or 5 1/4" and 10 1/2" (same difference).
I know that's not perfect thirds.  I think it folds nicely like this.

Admire your stack of handiwork.

3. Sew half the sandwich together on the tri-fold lines 
Align the Zorb over the bottom sandwich layer so that each fabric completely covers the other. Naturally, you'll want the side of the Zorb that has the lines on it to be facing outward.

Pin the two fabrics together thusly: 1 pin on each corner, then 1 pin per top and bottom edge in each of the three sections. You'll have 10 pins, so it'll be easy to count them when you pull them out.  Be careful not to place the pins too close to the lines.

 

Run some stitches through each of the two lines on every half-sandwich.  Trim any weird excess.

Straight down the center...

Nice job sewing.  Now you can remove the 10 pins!

Check out that tri-fold mechanism.  Pretty fancy.

At this point, I'm going to admit my mistake and tell you what I should've done, which means my pictures won't be so accurate from here on.  I made the mistake of stuffing these lovely tri-fold half-sandwiches into a sort of "pillowcase" I made by sewing three sides of the cotton top to the PUL.  When I pulled them out of the washing machine for the first time, all the half-sandwiches had bunched themselves up inside the "pillowcase."  I had to go back and anchor every half-sandwich to the cotton layer and it was kind of a pain.  This next step will help prevent this from happening to you.

4. Sew the half-sandwich to the sold white cotton
Place the solid white cotton rectangle symmetrically over the half-sandwich.  Roughly 1" from the short edge of the Zorb, sew the half-sandwich to the solid white cotton piece.  Now your cat pads will come out of the washing machine flat and lovely.  Won't that make your life much easier?

Alternatively, just include the top cotton layer when sewing your tri-fold lines.

5. Make sure your PUL is facing the right way!

Bust out the marker again for either the cotton or the "fabric" side of the PUL.  1" from each the edge, draw a line around all 4 edges of the rectangle.

Lay the absorbant sandwich on top of the PUL so that the shiny side of the PUL is contacting the absorbant sandwich (that is, so the "fabric" side is on the outside and the waterproof side is on the inside).
From top to bottom
1. solid white cotton
2. Zorb
3. fleece or quilter's cotton or whatever
4. PUL

Pin them together however you wish and stitch up all four sides.



6. Trim as needed, and serge if you can
Once you put the pee pad in the tray, you may notice that the pad is hanging out excessively here and there. You can either trim it now or see how it looks after its first wash (my cat pads shrunk a bit because I used a lot of cotton in them).

If you have a serger, this would be a great time for that.  My cat pads have started to fray with every wash; serging would be a great way to make them last longer!

7. Place, replace, and wash as needed.
My prototype lasted 3 days in the popular litter box.  At that rate, I'll be doing kitty laundry every other week.  Speaking of laundry, how do you wash these things?  Here are the recommendations I gathered from the two most important fabrics:

PUL Care: Machine Wash Cold Water, line dry. Do not press, do not use fabric softeners.
Zorb Care: Wash HOT, dry HOT, Bleach OK, no fabric softeners.

That's kind of contradictory.  So far I've been washing and drying hot, and they've been okay (with some expected cotton shrinkage, of course). The cloth diaper forums said you could wash these materials hot and dry them hot and they still last for years.  Mix some OxyClean in with the detergent when you wash them and the cat urine smell will disappear.

9. Use your scraps to make a nice "wet bag" for the dirties til laundry day.  Or get some kind of a odor-proof trash can. 
I found a Sterilite container that locks in the odors until laundry day and doesn't take up too much space.

So here's my final product compared to Purina's disposable pad:

And here's why I love the tri-fold feature:

Happy sewing!

Update August 24, 2019: Time to replace! I just started throwing some of my original cat pads out this year for getting ragged, so they've lasted about five years. 

Since the beginning, I've washed them hot and tumble dried them low or medium, which might be why the PUL is breaking down, since it prefers to be dried on a clothesline (which is probably a more environmentally friendly way to do it anyway).

If you've had success sewing and caring for your cat pads in a different way, or if you have any ideas for improvements to the design, please share in the comments. We can all benefit from the collective wisdom of the internet!