I would like a 30mm washi tape with perpendicular lines and checkboxes, so you can run it down the side of any notebook page or sheet of paper and make an instant to-to list.
MT does this measuring tape washi. To-do list tape would be more useful, and simple to adapt from this design. Please make this a thing.
Update 7 October:
I have found 45mm wide grid washi! I can work with a grid. My life is complete!
With a Squid Ink Pen 
I have a rubber stamp that has a to-do list with checkboxes on it. I could mask off the lines and just stamp checkboxes, I suppose. I suspect my to-do lists are a lot messier than are yours, to. 😀
washi, though! No stamp pad required. Just throw a roll in your everyday carry bag and BOOM, instant list, wherever you are. Leave a list for dinner prep for a teenager on the kitchen bench (or on the Doritos bag in the pantry) and just peel it up afterwards. Paste a list on your car steering wheel at night so you don’t forget to stop at the cleaners in the morning. Internet login instructions for your granddad. Stick a list on your pet’s medications pack. endless uses!