The material of the electrolyze: stainless steel 304

The thickness of the electrodes: thick enough to withstand the pressing without change in shape 

The dimensions of the electrodes: consider the current calculated

Taking into account the relation:

I = 0,4 x the surface that touches the solution=0,4 x A=0,4×3,14×r²

The cell voltage is U = 2,4 Volt 

The thickness of the gasket:

On the cathode side:  0,5 cm

On the anode side: 0,25 cm

The calculations must be done again taking into account the conductivity of the stainless steel 304

The resistivity of the stainless steel 304 is very small (0,72*10⁻⁶ (ohm meter)⁻¹) so it can be neglect and the calculations above are correct. 

The dimension of the endplates: a bit bigger in dimension then the electrodes and thin enough to withstand the stress of the screws 

The dimension of the wholes for the screw in the endplates: asking a mechanist

The dimensions of the screws: asking a mechanist

The type of the membrane: search it in google available and to be searched which one is the best:

Nafion n117 price: 340USD/pcs for 30*30cm. or 136USD for 15*15cm.

Nafion n115 price: 136USD/pcs for 20*20cm.

NR212 price is 303USD/pcs, 61cm*30cm.

NR211 price is 114USD/pcs, 20*20cm

Nafion N115 price is 136USD/pcs for 20*20cm

All the named Nafion membranes are from Alibaba:

https://www.alibaba.com/product-detail/Ion-Exchange-Membrane-Manufacturer-In-China_1600326782762.html 

The diameter of the wholes 

Of the water inlet: 

Of gas outlet:

The dimensions of the whole of the gasket based on the 

The dimensions of the catalyzer of the upcoming water vapor based on the calculation of the temperature of the cells and the amount of the water vapor upcoming.

The current = I = 0,4 x the surface that touches the solution=0,4 x A=0,4×3,14×r².