Imaging single particles using Free Electron Lasers can profoundly advance our understanding of chemical and biological processes. Electrospray injection is a promising sample delivery approach to achieve this goal and is hence used at the Single Particles, and Biomolecules (SPB) and the Small Quantum Systems (SQS) end stations at the EuXFEL. However, in particular two main challenges remain to be addressed. (1) To reduce background noise from injector gas flow, we seek to replace nitrogen gas in the Taylor cone chamber with helium, as its smaller atom cross-section reduces X-ray scattering. We engineer suitable nozzle tip geometries, to maintaining a local stream of nitrogen and carbon dioxide to locally protect the Taylor cone from corona discharge. Injector nozzles are precision 3D printed using two photons stereolithography. (2) To improve the hit rate of the single particle, we explore nozzle designs to improve single particle injection density to increase the hit rate.