There are many clones of which only one or two bricks are occasionally met. But there is a particular clone which is recurring. I have not been able to determine its brand name until now, and so I use to call it "X" but it is better known for its nippled studs.

I have "X" bricks in the sizes: 2X2, 2X3, 2X4 and 2X10, all of them good copies of the early ABB and later LEGO Mursten. But fellow collectors Richard Bintanja and Sven Köppchen sent images of 1X2 sized bricks. Richard also sent images of a 12X22 (!!) baseplate not unlike 10X20vs02 of LEGO and even wheelled 2X4 bricks.

There are, however, several telltale differences. The one embracing difference is the material- a hard and breakable plastic that wears easily and is quite different from LEGO but, ironically, quite steady and warp-free. Then, the X brick mold has a differently shaped stud, with a small nipple on top (see the three bricks on the left side of Figure 1 below). Apparently, the purpose of this nipple is to provide a small reserve of plastic to try and avoid the cave-in of the stud on fast injection cycles. But this purpose is not always served as shows the 2X4 yellow brick at the center right of figure 1 below, in which the studs depict a severe case of cave-in. The phenomenon is caused by the deflation of the injection pressure and opening of the mold too early in the cycle, while the thick studs are still soft. The results are dramatically illustrated by the 2X10 transparent brick of Figure 2, in which the whole spectrum is illustrated when you consider the lenght of the brick. On the left side the nipples are standing proud while on the opposite side the center of the studs caved-in entirely. The span of the brick depicts all the transitional situations.

Finally the mold cavities are marked with a faint letter, that may have been diamond-engraved after the mold was tempered. This means that the earliest bricks manufactured with the mold may have been unmarked.

"X" windows and doors are depicted on Figure 3 below. It will be noted that the doors are equipped with a spy-hole and the windows are different from LEGO's.

Several fellow collectors are of the opinion that the X-clone (or nipple-bricks) is indeed a genuine early LEGO product. However the doors, windows and, most of all, the baseplate show that the manufacturer was careful to distinguish its product from LEGO's, which he would not have done if he was under LEGO's umbrella.

It is not however impossible that the molds for the bricks and features was originally produced for LEGO and for some reason was then used by another party. But this is certainly not a LEGO product. It may, however, be the predecessor of the PUWI bricks which avoid the cave-in by hollowing the studs from the top, as did LEGO on its glassed windows.

follow the links for images of a large group of X-material from the collection of Eric Strand:

picture 1; picture 2; picture 3; picture 4 (all photographs courtesy Eric Strand)

My thanks to Richard Bintanja who called my attention to this group