## 3 Conclusions  
In the framework of the FrexiProb project, we designed and built a sample environment for the investigation of soft matter thin films via GISANS for the use at the ESS. The presented setup includes four core components: a spherical, 3D printed humidity chamber; a gas flow control setup; a spectral reflectance measurement setup; and a motion control system. The 3D-printed spherical humidity chamber with embedded fluid channels is optimized to reduce condensation and provide a homogeneous temperature distribution around the thin film sample. Temperature simulations and measurements show a layered temperature profile for temperature switches, with no significant temperature gradient even over large samples. The three-channel gas flow setup provides well-controlled mixed vapor atmospheres of pure nitrogen and two solvents. Gas compositions within the chamber can be easily adjusted via the regulation of the flow rates of the three channels. Laboratory experiments confirmed the accurate control and a humidity of 96%RH was achieved for an exemplary water saturated gas-stream despite the large chamber volume. The spectral  
Figure 9: (**a**) Wiring of the motion control unit for the four axes. M1–4 and E1–4 correspond to the motors and encoders of the 4 axes (LS-180 is axis 1). The EtherCAT terminals (ELXXXX) control the power supply and data flow of the encoders and motors. (**b**) Photograph of the assembled control unit.  
reflectance measurement setup installed on top of the chamber lid enables in situ thickness measurements during neutron experiments. Exemplary measurements demonstrated the functionality of the setup. Finally, the motion control setup consisting of four axes for lateral (perpendicular to neutron beam), vertical, and angular movement enables the accurate positioning of the sample for alignment and experimentation. The custom assembled control unit is based on the Beckhoff EtherCAT technology and optimized for future integration at the ESS. Thus, for the ESS instruments, a versatile GISANS sample environment that can be used for early science at the ESS is available.  
Conceptualization, R.v.K., T.H., and P.M.-B.; planning and discussion of setup components, T.W., L.P.K., M.K., A.J.S., L.W., S.J., H.F., O.L., H.S., and A.H.; construction and test of setup components, T.W. and L.P.K.; writing--original draft preparation, T.W.; writing--review and editing, L.P.K., M.K., A.J.S., L.W., S.J., H.F., O.L., H.S., A.H., R.v.K., T.H., and P.M.-B.; visualization, T.W. and L.P.K.; supervision, P.M.-B.; project administration, T.H.; funding acquisition, R.v.K., T.H., and P.M.-B. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the German Federal Ministry for Education and Research (BMBF) within the project \"FlexiProb\" sample environment grant number 05K2016.  
Not applicable.  
The derived data supporting the findings of this study are available from the corresponding author upon reasonable request.  
We gratefully acknowledge the ESS Motion Control Group for help implementing the control of the translation stages. We thank [PERSON] for fruitful discussions. We thank [PERSON] and [PERSON] for valuable discussions and testing of setup components.  
The authors declare no conflict of interest.