x1 is a tile/cake [shape/form] of material x2, shape x3, thickness x4.
A tile is a 3-dimensional object, relatively uniform and significant in the 3rd dimension, but thin enough that its shape in the the other two dimensions is a significant feature; 'city block' is conceptually a tile; polygon (= taplytai or kardytai - shaped like an approximately-2-dimensional block, lijyclupa - a loop composed of lines). (cf. bliku, kubli, matci; karda, for which the 3rd dimension is insignificant, bliku, kurfa, matci, plita, tarmi)