IKEA makes a great Detolf glass cabinet, but you might wish it had twice the number of shelves to make better use of space. As it turns out, IKEA also makes a standalone Billy glass shelf that is just the right size to fit within a Detolf. With these supports, you can mount it as an accessory shelf above one of the existing shelves.The design includes a lip that protrudes off to the side, which fits snugly between the lower glass shelf and the glass wall. This gives it additional stability. Note that this makes it incompatible with the lowest shelf of the Detolf (which is not glass, and does not have a gap to fit the lip), although the design could be easily modified to remove the lip for that application.Instructions1) Adjust the SCAD file to your liking, if necessary. Most importantly, the h variable controls the height of the main support - in the supplied file, the support is 150mm tall from the base to the bottom of the Billy glass shelf. With 3.3mm feet and 4.8mm glass, that means the top surface of the upper shelf will be 158.1mm from the surface of the lower shelf.2) Print the piece 4 times. For a consistent look, mirror it for two of the prints. This allows you to have a consistent side (top or bottom, take your pick) facing the front on all 4 corners. Tested with PLA, but ABS ought to work.3) Remove the rubber stopper from the plastic screw in the brackets that came with the Billy shelf. In this application, it doesn't help, as it just adds wobbliness and play to the finished shelf. As the screw itself is plastic, it won't damage the glass shelf.4) For each support, attach a bracket using the supplied metal screw. The screw will self-tap into the plastic. Keep the bracket approximately level (wide side down) and tighten the screw firmly. It helps if you pre-tap the screw a few mm into the piece first, without the bracket, to ensure it goes in straight, then remove it and replace it with the bracket in place.5) Insert some kind of item into the bracket (e.g. the shelf itself, or a screwdriver), tighten the plastic screw. Then, using the item as leverage, rotate the bracket until it is at 90° to the support.6) To lock the bracket in place and prevent it from rotating, apply some superglue to the edge of the bracket. The superglue should wick in slightly, particularly at the top and bottom. The combination of the superglue, to stop rotation, and the pressure from the screw, to stop separation, will result in a very strong bond. If you mess up, it is possible to remove the screw, rip the bracket off from the printed part, clean it (as it is metal, the superglue can just be scraped off), and repeat the process with a fresh print.7) Apply the rubber feet to the 4 supports.8) Attach one support to one corner of the Billy shelf and tighten the screw.9) With the remaining 3 supports handy, bring the shelf to the Detolf and carefully slide it in. Allow the support that is already attached to slip into place between the bottom shelf and the outer glass wall. You may need to re-center the bottom shelf.10) One by one, slide in the remaining 3 supports, while keeping the shelf balanced. You can leave the screws loose for now, though having them pre-adjusted to the point where the shelf slides in snugly helps.11) Ensure the alignment of all 4 supports matches, and that they are perpendicular to the shelf, then tighten the screws. Hint: a flathead screwdriver of the right size can work better than a Philips screwdriver on the easily damaged plastic screws.12) All done! Put things on the shelves and enjoy.