The fibrinogen scaffold was transferred into a petri dish with sterile ddH2O. Using a pipette, the scaffold was carefully detached by flushing it from the glass coverslip. Then, the detached scaffold was carefully transferred to a second petri dish using forceps. By slightly touching the scaffold with the forceps, it was centered above the PVC ring. To settle the scaffold onto the ring, the water level was decreased using a Pasteur pipette connected to a vacuum pump . Subsequently, the second ring was placed on top of the settled scaffold and three nuts were placed onto the screws. Both rings were screwed together with the 3D printed hexagon spanner. Finally, the clamped scaffold was transferred to a 6 well plate with sterile ddH2O.