This is a parametric clone of the well-known BILLY Bookcase from Swedish international home products company IKEA.TODO: holes for holding shelves boltsVariablesGeneral width → total width height → total height depth → total depth pthick → Planks thickness shelves → Number of shelves, including the top one but not the bottom one. It matches the number of gaps between shelvesSkirting board A skirting board or baseboard is a board covering the lowest part of a interior wall. In presence of a skirting board, most pieces of furniture need a gap in order to keep it close to the wall skirting → you can choose wether to use a gap to avoid skirting boards (true/false) sbdepth → skirting board depth sbheight → skirting board heightBack plank Back planks are usually made out of plywood back → you can choose wether to use a back panel (true/false) bthick → back plank thickness