A lightweight, foldable/portable dog water bowl! Handy when you're walking your dogs, especially during the summer.

Step 1: Gather Your Materials

Duct tape (two colors, if you want to be fancy)
Something to use as a bowl form (I used an upside down stack of styrofoam bowls)
A large plastic bag (like a ziploc)*
Scissors

*Mine was pre-chewed by my puppy but that's optional.

Step 2: Tape Your Bowl

Cut off the top of your plastic bag. It's better to have too much dog bowl than too little so leave plenty of the bag to work with.
Place the bag over your bowl form.
Add duct tape all over the plastic bag, pressing it down onto the bowl form. There's no right or wrong way to do this -- just layer the tape and cover the plastic bag. You'll later cut off the excess, so the tape at the bottom (which will be the top of the bowl when you flip it over) doesn't have to be perfect.

Step 3: Finish Your Bowl

Take the almost-a-dog-bowl off your bowl form. Press all sides between your hands or against the table to make sure the tape is secure. If you feel any thin areas, beef them up with more duct tape. The inside of the bowl will have loose flaps from the corners of the plastic bag. Somebody can probably figure out a nicer way to deal with these corners, but they don't affect the bowl's usability, so I leave them.
Cut off the top of the bowl so it's relatively even.
Fold duct tape over the top. I used a contrasting color to make my bowl extra classy.

And you're done! The dog water bowl may be stiff at first, but it will get easier to fold over time. Turn the bowl upside down to dry after use. This is only the second duct tape bowl that I've made (the first one was chewed by my toothy yet toothsome puppy), so if you have any questions, I probably don't know the answer. I can say that the bowl is pretty sturdy, and if it weren't for the puppy, I'd probably still be using the first one.