The best-known DT&I modeler I'm aware of is Jim Hediger, who's worked for Model Railroader/Kalmbach for quite a few years. His HO standard gauge layout was/is the Ohio Southern, and has been the subject of a number of MR articles.
You may be thinking of this one owned by Leon Sowell from Michigan, who models the DT&I Jackson Division. He was featured in the Model Railroader January 2003. Track plan below. It's a 15 x 22 foot HO scale layout.
Thanks all for your efforts to share this information with me.
I have a special interest in southern Ohio operations of the DT&I, particularly between Springfield and Jackson, OH. I had a chance to see some of the line in Waverly and Jackson years ago when it was still a going concern.
I'm considering some day building a module focused on Waverly with the N&W interchange there. Very interesting operation over Summit Hill where the grade called for "doubling the hill" at least sometimes and that area restricted to 4-axle motive power due to the sharp curves. It would be interesting to model the Summit Hill area, but it wouldn't be much to operate as I think traffic was relatively light.