For a one-year old, we have done a daily highchair time for 15 minutes. One day, we used an ice cube on construction paper that was taped to the tray. Another day was a paper taped to the tray with a bit of kool-aid powder sprinkled on the paper and a tiny cup of water and a large paintbrush. You can actually get several different packets of powdered kool-aid that are different-colored and only use a little sprinkle each week, saving them from week-to-week to give you different colors and still be economical.
Another day was a paint with water book page taped to the tray which the child painted with water. Another day was a Cheerio book that the child was given a cup of cheerios and used them to place on the pages of the Cheerio book.
Another thing we've found to work well in the high chair for that age is a set of very large magnetic balls and rods called Magneatos. I believe the 36 piece set was around $25 or so, and my little ones have played and played with them.
So, if you have a highchair, it would help so much to get thinking of things that could be done on the highchair tray. We typically sit next to the child while he's in the high chair during this time to oversee any spills.
Blessings,
Carrie