When dealing with bounce cards (a favorite solution for a great many issues) the problem becomes how to support the cards without taking up a lot of valuable table real estate. One solution I found is the use of a simple DIY holder made from discarded 2x4 pine studs. You can see them in use in this photo (circled red) holding up some black and white foam core bounce cards.
Their design is incredibly simple and can be done on any standard table saw. If you don't have a table saw of your own, consider asking a friend or relative to make these for you. A couple dozen can be cranked out in less than an hour. The beauty is that any scrap piece of lumber can be made into these handy holders.
Most two by fours will have slightly rounded edges. Don't worry about this as a bit of sanding on the cutoff side will even them out. I suggest taking some sandpaper to the finished pieces just to soften the edges and remove splinters.
Step 2: Once you have your smoothed, softened and squared stock of material you will need to cut them down to useable sizes. I found that a length twice the size of the width works well. It gives enough weight to hold up an eighth sheet of foam core board (roughly 5x8).
You can set the table saw rail to the appropriate spacing and cut the length into as many pieces as you have material for. You will want to make at least a dozen. If you need additional weight to hold up a card, simply add another holder to the opposite edge.
Step 3: Here you need to be a bit more precise. The groove you cut into the holder needs to be wide enough to allow the edge of the foam board to slide into it but not too loose that it falls out easily. That can be frustrating. Having a little grab is best. It allows you to place the holder in various places along the card edge without it sliding around (useful for angling cards). The depth of the groove should be one half the width.
If you care to spend a little more time with it, you can turn the piece 180 degrees and add a second groove on the opposite side. Not that it's needed, but it gives you options.
For larger cards, a second holder can be added for the extra weight. By inching the holder upwards along the edge you are able to angle the card back. To angle forward you simply need to turn the holder the opposite way.
If you look closely at my photo above, you will see that the holders also have a groove running the long ways. These were my prototypes and I quickly found that the long groove was rather inadequate. I also made smaller square holders but they are only suitable for holding really small cards. They don't have the weight to keep cards upright.
Feel free to make these for your own studio. If you find yourself making improvements on this design, share them with others by posting your findings here.