Call your local sporting goods stores and find out if they have (in stock!) a toilet seat that clips onto a standard 5-gallon bucket (they're about $10). One name is Luggable Loo. If they have the seats, they probably carry some buckets. Use a new one that hasn't gotten brittle sitting in the sun (about $6).

They're stable, they're easy, they can sit in the bathroom, and kids and old people can use them with no problem.

Find a garden supply (etc) or woodworking place that has sawdust. Fresh raw sawdust (directly from trees) is best, but sawdust from non-treated wood will do.

1. Line the bucket with a heavy-duty plastic bag that fits.
2. Clip seat/lid onto bucket.
3. Add about 2" of sawdust to bottom of bucket.
4. Keep another bucket or two of sawdust nearby.
5. Every time someone makes a deposit, add a scoop of sawdust over it.

When full enough, fasten bag securely and put it where you store stuff to take to the dump.

More complete info, see FREE online book The Humanure Book by Joseph Jenkins, including photos and drawings.
http://www.weblife.org/humanure/default.html

Sue