When my son was born we got loads of really lovely cards and then two weeks later it was my daughters second birthday and we got lots more lovely cards. I can be quite sentimental and didn't want to just throw them all away, but at the same time I didn't have the space to store all those cards. The solution? I decided to make a small canvas for each of their bedrooms encorporating the cards, and it is SO easy too! Score! (as my two year old would say!)
I started out with a canvas about 6 x 6 inches and painted a co-ordinating colour for their rooms. Just so you know, I used my daughter's non toxic play paint for hers and left over wall paint for my son's and they both look good and have held up well. Then while it was drying I punched out hearts from the cards, some plain and some patterned, then laid them out in a square shape till I was happy with the colour combinations and size. When the paint was really dry (overnight was long enough for me) I put a small foam pad behind each heart and stuck it on how I wanted.
For mine I wanted it central and even so I measured the mid point and worked the hearts outwards so they were 2cm away from each other. (Middle line first, and then the two above, then the two below.) But I think it would look nice as a heart shape or a few lines of them horrizontally or vertically. Also any punch would work pretty well to go with your theme, a star or butterfly or car, use whatever you have!
Then hang on your kids walls and look at how pretty and simple they are!
NOTE: Do not lay your hearts out for each canvas exactly how you want them the night before and not expect your small child to think they are confetti. She/he will throw them all over her breakfast/the kitchen floor. Not that I made that mistake of course. :)