DIY blender lid replacement
Any round piece of something that's reasonably solid will provide a start for a lid (think, arts and crafts store). Then trace around the top of the blender to see where the top of the container meets the lid. Then glue a foam-rubber gasket (DIY home store... windows) just inside the line and it should create a tight seal between the blender and the lid.

This will provide a makeshift but usable hold-while-in-use lid.