Maury didn't realize that thousands of people are interested in trains like he is and in 1974, while at the University of North Carolina, he was already earning through a small business as he sells train models through mail order. While his sales skyrocketed, he started believing that he can start up his own train company within the tinplate market.
Claims for more shipments with the ever growing increase in orders of his model trains, Maury Klein built a building on a piece of land near Chapel Hill, North Carolina and this is where his mail order business started growing by leaps and bounds. His father joined him in 1979 to help out in creating new train models- the O27 and the 'O' gauge track which are now under the MDK K-Line, which is an original brand and model.
MDK sold quite a number of Lionel Trains which was also sold by one of its major competitors the MTH Electric Trains. While Maury's mail order business grew, his ads appeared on well-known train magazines such as Model Railroader which was very famous towards the end of the decade 70's.
Another competitor, Louis Marx and Company closed down finally in 1978 and this marked the ascent of Maury's MDK K-Line of trains. Maury bought tooling and accessories owned by Marx previously and made use of him in his production lines and he was able to make some purchases of heavy equipment and manufacturing devices at very low prices. Maury was able to find tools used to be owned by Marx which he left behind as he went scavenging on the warehouses and factories wherein he found molds for Marx 1947 model #333 pacific and #1829 4-6-2 Hudson locomotives in an old abandoned Fisher-Price warehouse located near Buffalo, New York. It was told that they found the molds in the old abandoned warehouse where snow was falling off the roof and the warehouse didn't have any lighting or heating system at all.
Maury had acquired Kusan rolling stock dies. These dies are designed for building Auburn Model Trains which were American Model Trains as was earlier known. William Reproductions sold the dies to MDK K-Line way back 1986 and in the same year, MDK created a number of O27 locomotives, cars, and all other figures as well.