I printed all parts at .15mm vertical resolution with 20% infill.
I printed all parts on an Ultimaker 3 Extended in Ultimaker Red (extruder 1) and Ultimaker White (extruder 2).
"Heart.3mf" is the dual extrusion file for printing the heart figure. It required about 5 hours to print, 31g of red filament, and 7g of white filament.
"BannerXOXO.3mf" the a dual extrusion file for printing the XOXO banner. I required about 2.5 hours to print, 6g of red filament, and 10g of white filament.
"BannerBeMine.3mf" if a dual extrusion file for printing the Be Mine banner. It required about 2.5 hours to print, 2g of red filament, and 13g of white filament.
Banners can also be made by hand using thick poster board with colored pencils and/or pens. The grandkids are working on some banners for my wife on Valentines Day.
I've included single extrusion versions of the parts "Heart.stl", "BannerXOXO.stl" and "BannerBeMine.stl" for those wishing to print and paint the valentine.
After printing, simply slip the banner into the figure hands.