The spread of renewable sources has boosted the emerging Power-to-Methane (PtM) concept as an attractive strategy for turning surplus power into Synthetic Natural Gas (SNG). PtM is founded on CO2 methanation, a highly exothermic process that renders appropriate heat management challenging in conventional reactors. Hence Process Intensification (PI) may provide a breakthrough. This contribution presents a Computational Fluid Dynamics (CFD)-aided conceptual design of a heat-exchanger wall-coated methanation reactor. The design is based on a reactor formed by single-pass stacked plates comprising a reacting network of multiple channels coated with NiAl(O)x. The reactor is evaluated at industrially relevant operating conditions with an undiluted stoichiometric feed. A 3-D reaction channel is parametrised to define a design point that guarantees a minimum CO2 conversion of 95%, maximising throughput without hot spot formation. The plate manifold is 2-D dimensioned to keep an even flow distribution as a function of the number of channels. The entire stacked plate is 3-D simulated to corroborate the findings of former design stages and discuss the effect of the length of the channels on reactor performance. The proposed conceptual design sets a feasible PI base case to overcome the shortcomings of conventional reactors for PtM applications.