In my project, I have designed not only a spool holder but an accessory to make printing easier for you. I have created a part that you can add to your shelf and this part will guide 1.75 and 3.00 filament across your shelf to any printers that are far from your spool holder. This will create a more organized, and clean working enviornment for you. This will reduce the odds of someone or something snagging onto your filament and causing a print to fail. This will also allow you to access your filament above the Filament Guide. This accessoty has two parts to it. The main part is the FILAMENT GUIDE BASE and the other part is called FILAMENT GUIDE SCREW ATTACHMENT. To assemble this, you simply screw the SCREW ATTACHMENT into the GUIDE BASE. Screwing the screw on at first may be difficult so check to make sure that there is no excess filament covering the screw or any other item preventing you from screwing it on. With the movment of the screw, you can angle the screw to obtain maximal range of movement as your filament slides through. You may noticed that there is a gap in the side of the screw. This gap allows you to easily remove and input filament. The 3.00 Filament may be a tight fit to get through but that was only to prevent the filament from falling out easily. Also when you use the Filament guid, keep the open gap in the screw faced up to prevent the filament from falling out. In terms of attaching these to your shelf, given your measurments of 1.5x .75 inches, these will slide on from the top and the clips at the bottom will prevent the Spool Holder and Guide from falling off. To remove the holders, you press onto the clips on the bottom and lift up. The Spool Holder can fit a spool of filament up to 2.25 kg. Anything larger will not fit onto the rod. Thank You.