If laid down flat, you would probably want to make sure they are fully supported in the middle of the playfield so they can't bow over time.
Im confused on this? If laid FLAT how would they bow on a FLAT surface?!?
As mentioned in my post, I was referring to playfields in boxes. If they are in a box, as most playfields are shipped and stored in, the packing and support is on each corner of the playfield with no support normally under the centre of the playfield. Step on it or inadvertently put some weight on it and there is a chance of damage.
Playfields take up much less room standing up and as long as the edges are protected should be quite safe.
