This needs to be moved to the Teachers Discussion Forum. You'll be able to get great input from more experienced reading teachers in that location.
The first thing you need to do is to decide the reading level of the children who will be using your kit. The kinds of activities you would include in a reading kit for kindergarteners are very different from the activities you would include in a kit for middle school or high school advanced readers. Since they are my favorite age, I'll provide some suggestions for the youngest students - the ones just learning about letters and sounds.
At that level, you need lots of hands-on activities allowing students to make the connection between the symbol on the page and the sound they should be associating with that symbol. Cards with a letter on each card can be matched with pictures of objects having the initial sound represented by the letter. The sounds represented by the cards can be acted out through hand motions corresponding to words starting with that sound (zipping motion for z, make two fingers run for r, and so on). Matching games are valuable - picture boards with objects representing a small number of initial sounds and picture cards to be drawn and matched with the picture on the board that has the same beginning sound. Provide sheets to trace the letter with a finger before coloring the object that features the sound. If you have access to lots of magazines, provide scissors and paste so the students can find, cut out, and mount collages of pictures representing the same initial sound.