The existing designs of the 16 T dipoles of the Future Circular Collider (FCC) consider the use of Nb3Sn grading. Since 2017 a collaboration between CERN and Swiss Plasma Center has been aiming at developing and qualifying intergrade splices. The main goal is obtaining a low electrical resistance (<1 nΩ) at magnetic field higher than 10 T and at a ratio of 1/3 between operational and critical current. Such splices would preferentially be internal splices, i.e. inside the winding pack. One solution is crimped-soldered splice between overlapped cables. Its manufacturing and test in SULTAN is presented in this talk. Preliminary results show also that diffusion-bonded splices are a “clean” potential solution, in the sense that they would avoid the use of fluxing agents. However, their implementation inside a dipole is more complex and must be demonstrated. With this purpose, in this talk, the design of a single pancake racetrack model-coil is discussed. One diffusion-bonded splice is located at each end of the coil, following the curvature in order to reduce the space occupied. The splices form during the coil heat treatment. As diffusion-bonded splices require pressure at high temperature, the clamping fixture that applies the required level of pressure is designed under the constraint of limited space availability for its assembly. We will present progress towards the construction of this model coil, which is expected to be tested by the end of 2019.