I used guides in Photoshop to align the pictures on a 4x6 screen. This way I could make straight cuts instead of cutting out each picture individually.
Then print out the pictures on photo paper
And using a glue stick, apply an thin layer of glue on the back of the 4x6 sheet.
Ooooh nice and glue-y
Glue the sheet(s) to a sheet of chipboard (I got mine from an art supply store for less than $2), and lay clear packing tape over each set of pictures. Be CAREFUL when placing the tape... it's ridiculously easy to mess it up and end up having to print out a whole 'nother sheet (like I did 3 times).
Use something blunt and flat like a pencil eraser to smooth out any bubbles between the tape and the picture. If there are any stubborn bubbles, us a pin to prick a hole in it, then smooth as usual.
Use a ruler and an xacto knife to cut out the pictures. If you lined up your pictures correctly, you should be able to cut straight lines vs cutting each out individually.
Stack up all the polaroids and take a picture. Sit back and marvel at how far you've come.
The art supply store I went to didn't have magnet rolls, so I just went to Five Below (a discount store, everything is $5 and under) and got a couple of large magnets.
Use the xacto knife to score the surface of the magnet. I think this will help the glue stick better, but I have no proof.
Lay out all of your polaroids on top of the magnets to make sure you have enough. Somehow I did, even though it doesn't look like it.
Use a pencil and ruler to mark out cutting lines on the back of the magnet. I made mine 1/8" shorter than the length and width of the polaroids.
The pencil lines came out better on this one.
Cut with scissors.
Use the glue stick on the image side of a magnet square.
And center it on the back of a polaroid.
Again, stack and marvel.