(written from a Production point of view)
During the the late 1980s and early 1990s he was employed at Science Fiction Modelmaking Associates (SFMA) as propmaker and has contributed to the manufacturing of the various items that company produced for the Star Trek: The Next Generation series during their season three-five run. Horch was also team member on the prestigious assignment of the eleven-foot Constitution-class studio model restoration for the Star Trek Smithsonian Exhibit of 1992.
It was Horch, an avid Star Trek: The Original Series fan, who had constructed the replicas of the Original Series captain's chair, and helm and navigational console, for convention purposes and slated to appear in the 1993 Star Trek Earth Tour traveling exhibition,  that were used in 1992 in The Next Generation episode "Relics".  Discovered shortly before the start of the tour by Michael Okuda, who flat-out stated, "If not for Steve Horch, we would not have that scene.", they were rented for the recreation of the original Constitution-class bridge in the episode. (Star Trek: The Next Generation 365, p. 548) Returned to Horch after use, the now bonafide screen-used set pieces continued their existence as tour displays, as well as later serving as masters for additional copies to commercial ends. Knowing that these pieces were out there, served the franchise well on a subsequent occasion six years later, when both pieces (or copies thereof) were again rented from Horch for the Star Trek: Deep Space Nine episode "Trials and Tribble-ations". Everything [remark: the sets] except helm and Captain's chair, were built for specifically T&T. We rented those from Steve Horsch [sic.], a big fan who was also a professional Hollywood prop maker. Almost nothing is left over from the 60s, set-wise. So we built an entire corridor of the original ship, and parts of the bridge., Doug Drexler confirmed. 
After SFMA went out of business, Horch went on to found HMS Creative Productions, Inc. in 1998 with fellow prop maker Michael Moore. Continuing where SFMA left off, he and his company, proceeded to provide the Star Trek franchise with props and models.
Apart from the official franchise, Horch, on personal title, has also provided props for James Cawley's non-profit internet fan series, Star Trek: New Voyages, which, again, included the construction of a captain's chair, and helm and navigational console. Reminiscent of what Horch had done earlier on personal title, Cawley rented out the "targeting scope" part of the helm console to the franchise for use in the Star Trek: Enterprise season four episodes "In a Mirror, Darkly" and "In a Mirror, Darkly, Part II".