After getting a 3rd sheet (the neat satin one), I needed to be able to hold 2 sheets while printing with the other one. This adds a middle section to the excellent sheet holder that attaches to the spool holder rails. You can use one or more to be able to hold as many sheets as you'd like. You'll need longer M3 bolts than the ones for the single sheet, 18mm or 20mm works well for a single middle section.