Other advances improved plant efficiency and eliminated production errors. Eli Lilly, grandson of the company founder, introduced a method for blueprinting manufacturing tickets in 1909. This process, which created multiples copies of a drug formula, helped eliminate manufacturing and transcription errors. In the 1920s Eli introduced the new concept of straight-line production, where raw materials entered at one end of the facility and the finished product came out the other end, in the company's manufacturing process. Under Eli's supervision, the design for Building 22, a new 5-floor plant that opened in Indianapolis in 1926, implemented the straight-line concept to improve production efficiency and lower production costs. One historian noted, "It was probably the most sophisticated production system in the American pharmaceutical industry." This more efficient manufacturing process also allowed the company to hire a regular workforce. Instead of recalling workers at peak times and laying them off when production demand fell, Lilly's regular workforce produced less-costly medicines in off-peak times using the same manufacturing facilities.