Rare earth magnets are regularly used for installing works on paper and textiles for digital imaging. As the prior poster said, anything that can be imaged flat on a surface should be.

For pieces that are larger we use a magnet board. We use a 4'x6' one on a wheeled stand that can swivel horizontal and lock for placing artworks before applying magnets. Also, an 8' x 5' board (aluminum core with a powdercoated steel surface) that is mounted on a large easel at approximately a 75 degree angle. The steep angle of the large easel mounted board allows the camera the distance and height to get the entire 8' if needed.. The large magnet board also doubles as a slant board on which to place matted works which are securely matted (hinged) and can be safely placed at a near vertical for imaging. We attach a piece of 1/2" foamcore with embedded magnets (1/4"x1"x2", really painful to get fingers pinched) at the bottom of the magnet board for this. Using the magnet board as a slant allows stronger magnets to be used to secure the backing board and the window of the mat.
Depending on the type of 2D work being installed, we will use buffers such as tyvek, photo-tex, .03mil mylar, blotter paper, or other materials requested by conservation. Please keep in mind that the stronger the magnet, the more likely it can damage the surface (emboss, tear, etc) of the art. The reduction in friction from buffers is something that must be considered as well. For more permanent buffer, I have tried tyvek tape, but the adhesive slips. Same with a few other archival tapes..I also tried heat shrink plastic tubing, but that didn't worked and I ended up just burning my fingers... If anyone comes up with a good permanent buffer please share.

We typically use round disc magnets from approximately 1/8"x1/4"x1/4" to 3/16"x 5/8"x5/8" are used to secure artworks around the perimeter with smaller magnets such as 1/32"x1/16"x1/16" used to help minimize any buckling and hold down isolated areas such as torn edges. Really thin magnets break quite easily. You will need to watch for bits of magnet and iron filings which can leave marks. I try to use the least amount of magnets to minimize any potential damage, yet still enough to feel the artwork is secure. I would rather use a couple dozen very small magnets instead of 4 stronger ones if the piece is very fragile. Sometimes up to 40 or 50 magnets will be used such as when installing silk which requires the weave and weft to be kept "square".



Another small stack of magnets can be used for removal by holding the attractant end directly above and magnetism will do its thing. This can help avoid dragging magnets across the surface. Also, the use of many smaller magnets may be preferable if post-editing by the photographer is needed to avoid showing the magnets.

We do have a few methods for using magnets on walls, but we tend to avoid this for all but the largest pieces.