You already have a Combo / Drop down list with multiple columns, what I think you want is the row value displayed in the list as your ControlSource value, right?
In converting from Foxpro for windows, where we used a Mono-spaced font with multiple items concatenated and chr(124) as a vertical bar separator, we converted to Arial,8 and then used PADR() with a twist... we converted the alltrim( value ) for each item in the list to pixel width ( reference FontMetric(), TxtWidth() functions ) and padded to that width between the pseudo vertical bar.

Caveteats -- chr(124) in Arial doesn't touch so there is a slight gap in the bars between rows -- chr(179) in the Mono-spaced world does touch and with the mono-spaced font looks reasonably well. Mono-spaced does not look like "Windows" or so our marketing people say. It is a "look and feel" decision.