By mounting large puzzles in sections, they are easier to handle, hang and transport if you move, and you could also rotate them out if you don't have room on your walls for all of them.
I haven't had an issue with flipping 1000 pieces at once, and when I went to flip African Animals, I had it split into 4 sections of 750 pieces each. On the third section I must have been a little too slow, because this happened:
Here I have drawn the lines which will separate each section. The strip in between will not be covered with adhesive or the foam boards. This allows the sections to separate. As I found in mounting attempt 4 and fixed in part 2, this gap is needed so that the pegs from one side can go behind the holes from the other side.
This is a close-up of the center of the puzzle where the gaps in the foam boards will meet.
I didn't realize until after the fact that this picture came out a bit blurry, but you can see the outlines drawn where each piece will be cut.
Here the foam boards and cut and lined up where they will be once the mounting is complete. On the sides you can see the notches I made such that you don't see the gap between the foam boards from the sides. I goofed and forgot to make these for the top and bottom, but since this is a large puzzle you can't tell.
Here I have wrapped the edges with black duct tape to give them a nice finished look.
This is a close-up of the notches where the gaps meet. It's not necessary to cut away the foam board between the edge and the first peg on each side. This allows the gap to not be seen from the sides.
Here the adhesive has been applied and the backing paper is still on. This is the gap between two of the sections where the adhesive will not be placed.
Here the adhesive has been applied to most of the puzzle. I prefer to roll it out on the puzzle and then cut it with an X-acto knife, instead of measuring it out and then laying it down. For the smaller sections you can overlap the adhesive off of the roll and then cut away the overlap, since the adhesive does not stick to the backing paper.
Once the adhesive has been applied to the whole puzzle, you use the supplied squeegee to apply firm pressure (in both horizontal and vertical directions) to the adhesive. This makes the adhesive permanently bonded to the back of the puzzle.
This is what it looks like as you peel back the backing paper. The adhesive is transferred to the puzzle, and the backing paper will no longer be sticky at all. If you see the adhesive not transferring (pulling up too much, a little more than seen here), you can simply lay the backing paper back down in that section and apply more pressure, and then try again.
Here the backing paper has been removed from a section. I've found that I prefer to apply the adhesive to the whole puzzle, then remove the backing paper and apply the foam board to each section one at a time. This way you don't have the adhesive exposed on the whole puzzle at the same time. Here the foam boards have been applied to two sections, the adhesive is exposed on one, and the backing paper is still on the fourth section.
A close-up of the adhesive on the back of the puzzle. You can see that it fills in the gaps. This makes it such that even with a loose-fitting puzzle, the pieces don't move as the backing paper is removed.
After applying the foam boards to each section, I applied firm pressure to the back of the foam boards. You could use a rolling pin on the back of the foam boards to apply the pressure. I then very carefully separated the sections. With a smaller puzzle it's possible to flip it all at once, but with a large puzzle you can't flip the whole thing while all of the sections are connected. Once the sections are separated and flipped, the supplied protective sheet is used between the puzzle and the squeegee to protect the front of the puzzle. Firm pressure is applied in both horizontal and vertical directions. Along the seam edges, don't apply pressure to the half of the pieces which hang over the edge of the foam boards. If you lightly press on these overhanging edges, they do move a bit, but I think part of this is that Ravensburger pieces aren't as stiff as other brands so they flex a bit.
Here, pressure has been applied to the front of each section, and the mounting is done!
A close-up of the edge where two of the sections meet. If you wanted to, you could use a small strip of tape over the seam on the edge, and then just slice if when you need to take the puzzle down.
The sections re-assembled:
A close-up of separating the sections:
I used the "large" size Command strips, which are rated at 16 lbs each, so they're a bit overkill but that's not a bad thing. I avoided placing them near the seam edges on purpose so that when the puzzle is take down, force won't be applied near these edges as it's pulled off the wall.
Mounted on the wall!
Read about additional mounting projects here.