Tools and materials:
50mm A0 size polystyrene/styrofoam
Step 1: Mark Cut Out
Measure the dimensions of your tablet and place a holding image of the tablet PC on the poster where you want people to interact with it. I suggest somewhere towards the top, otherwise some people will need to stoop or bend their legs to use it.
The polystyrene/styrofoam that I am using is insulation. It cost about £13 for a 2m sheet from a local DIY/hardware store. Cut this to the same size as your poster.
Cut the sides and bottom of the holding image. Do not cut it our completely. You may need to use the poster without the tablet PC and it will look a bit strange with a big hole in the middle.
Place the poster on the polystyrene/styrofoam and make sure it is aligned.
With a marker pen draw on the polystyrene/styrofoam the outline of the rectangular hole so you will know where to cut a rebate in the polystyrene/styrofoam. Remove the poster.
Step 2: Cut Out Rebate
You may find it easier to remove the polystyrene/styrofoam in strips and levering out the small chunks as you go. Tray and make the fit as snug as possible so that the tablet PC will not fall out.
If you find that the tablet PC is a bit loose. You can cut out some cardboard corners to hold the tablet in using the template image as a guide. Once you have them, fold along the lines.
Take a knife and cut a right-angled slot near the corners of the rebate, making sure they are the same size as the cardboard flaps. Slot the folded flaps of the cardboard into the styrofoam making sure that the cardboard corners overlap the corners of the rebated area. Repeat with other corners. The cardboard/styrofoam should offer plenty of resistance, preventling the tablet from falling out.
Don't forget to place your tablet in the polystyrene/styrofoam space. Though you will really need to do this when your poster is in situ.
Step 3: Finally
After you have mounted the polystyrene/styrofoam you can then pin your poster to the polystyrene/styrofoam. Fold the flap of the holding image backwards and up behind the poster to place out of view.