FIGURE 6 ACCELERATORS AND ENGINEERING DIVISION SYNCHROTRON SOLEIL HIGHLIGHTS 2020 Captions FIGURE 4: BPM first prototype with 3 mm diameter buttons a 10 mm diameter block (left), inside view (center), support (right). FIGURE 5: 57 to 60 mm length RF-shielded bellow mechanical prototype (without membranes). FIGURE 6: Picture of CPMUE32 prototype with a 6 mm diameter aperture (center) and magnets for magnetic force compensation (off-center: top, bottom, left and right). FIGURE 7: Mechanical design of the proto-CPMU12. Up: dark blue: Magnets. Gray: poles. Bright yellow, light blue and magenta: clamps. Light yellow: keeper. Down: Assembly of top and bottom keepers. A prototype of CPMUE32 is under construction, in order to validate the assembly of the magnets, the magnetic force compensation (addition magnet row), the liner holding (Figure 6). In the hard photon energy range, the search for small period length with thin magnets and poles pushes the technique of pole-magnet-pole keeper to the mechanical limits. A prototype of few periods of 12 mm (Proto-CPMU12), installed on 8-period keepers, is under construction for checking in particular the mechanical tuning, the accuracy of positioning of magnets and poles and the rigidity of keepers (Figure 7). FIGURE 7 99