Sometimes projector linchpins are just not long enough to align the projection with the screen. And just then, according to Murphy's law, no book is available as a makeshift extension.

This 3D-printable extension lets you raise the projector an additional 25 mm. So just add it to your projector bag, it is smaller than a book. Depending on the projector type you may have to print two of them.

As always I include the OpenSCAD source file for you to adapt or improve:

• Download and install OpenSCAD from https://www.openscad.org
• Launch OpenSCAD and open the enclosed OpenSCAD source file (/File/Open).
• Amend the parameters at the top of the file and/or modify the source code.
• Save your changes (/File/Save).
• Render the design (/Design/Render).
• Export the rendered design e.g. as a .stl file (/File/Export/Export as STL).
• Slice and print.

See my other designs at
https://www.thingiverse.com/thinger13/designs