[If you can find a second hand one of these, or if someone with skills could make one, that would be great! They seem to be really expensive everywhere I've looked.] Montessori Cube Chair by Floorbeds for Fae
This word building activity travel kit is perfect for preschoolers for road trips and long car rides and you can customize it with sight words, color words, word families, or whatever your child is currently learning. Great for a summer learning activity.