Time for an update on this.
I have tried two different brands of formed recycled paper liners, the Nature's Miracle brand large, and the Kitty Wonder Box, medium. Though the Nature's Miracle size large is $10 more (for the same number) and claims it's sides are 6.5 inches high, the fact is the NM size large boxes are only 3.5 inches high, and a half inch narrower than the Kitty Wonder Boxes. So I will stick with the Kitty Wonder Box medium, for my regular sized litter boxes for now, though I will keep looking.
For the large tote litter boxes I needed something else. I had tried just lining them with cardboard (boxes, cut to fit) but this was only partially successful.
The sides of the box pieces I was using were sometimes shorter than was practical, meaning when the girls do their stand up and pee routine in the high sided box the pee and subsequent litter would get behind the edge of the liner, making a mess and smell underneath. Also, there was some overlapping of box edges, the between of which, again because of the stand up pee-ers, would get wet and smelly.
When my next order of liners came they came in a box that seemed to
almost fit the large litter box. My brain got to whirling a bit.....I wondered if I could wet the box and re-shape it, you know-mold it to the litter box shape.
doesn't quite fit
once wet, (with the flaps torn off) it was made to fit
because of the 'gap' between the two flaps on the bottom of the box, I cut another piece of cardboard just the right size and inserted it, also wet, in the bottom. I don't know yet whether this will be dug up by the cats when in use or not. I will report when it is used.
Final result
As you can see above, one end kind of..buckled, and doesn't fit flush to the box side. This also might be a problem, as Jennie is an avid side scratcher. So next time I do it, during the molding step, I will put a stack of other litter boxes in it, to keep the sides pushed back.
OR, I just realized, I could get one more of the high sided tubs, and use it as the top of the mold. But I'll try the stack of litter boxes I already have first. No point in buying another box that I really don't need, limited space being what it is in this apartment.
Any other ideas about helping the cardboard mold to form are welcome.
So I will use the formed recycled paper liners in the regular sided boxes and the home made cardboard liners in the large boxes, and my days of back breaking rinsing scraping, scrubbing, drying and airing are over.
PS I've discovered that those pre-formed paper liners can go a whole month without any odor starting.
Time will tell, on the home made liners. Plastic boxes start stinking in about 10 days.
PS the savings in amount of litter used (with fewer dump and scrubs), not to mention the bleach, soap and vinegar used to clean and rinse them, I think may even out or even over-compensate for the cost of the liners. Let's see, the liners, if I only have to change them out once a month, will cost $6 a month.
Since, in my old method, I was going through a jug of litter a week (at $6.99 a jug), and the new method, with only starting new litter once a month, just topping off the boxes when needed, I am using only a jug every two weeks, yep, there is savings!
Old method: Litter used = $28 a month, and back breaking work every week.
New method: Litter used = $14 a month, liners =$6 a month. Total monthly cost $20 total monthly savings: $8. (not counting soap, bleach and vinegar use, not to mention hot water) And no back breaking work. Whoo hoo!