Material Emulation Screen
Simulate the chemical properties of a surface through electric field patterning, and get electrons simulate materials without use of atoms.
Traditionally, what determines the chemical and physical properties of materials, is largely, how electron field gets arranged, when electrons encounter the force fields around nuclei. We traditionally rearrange that through introducing or taking away electrons to get new materials. However, nuclei are just sources of point-like positive electric charges. If we could simulate those point-like charges in other ways (like through directed positronic fields), it is not inconceivable, that one day we could create an equivalent of "computer screen" that simulates the surface properties of arbitrary materials including their chemical properties, without having any baryonic matter at all. This would likely be useful for generating arbitrary reactive surfaces to catalyze various chemical reactions, play "pong" with particles.
Given that we already have positronic sources, and advanced electric field manipulation techniques, we could start playing with releasing them in streaks, in geometrically peculiar ways, such as to make them form electron-positron rings, or helical structures, seeking for more stable standing patterns, that remain sensitive to input conditions. Such search for patterns eventually could result in discovery of positronic-electronic standing fields that do the trick.
Disclaimer: I'm not a physicist, but this, while highly speculative, seems like a logical possibility. It would be great to have an input from physicists with deeper knowledge into this domain.