I'm trying to write a macro that will apply a bottom border to every
other cell in a range. the macro only needs to work for horizontal
ranges, and not for vertical ones.

the closest i can get is the code below, but this only applys borders
to cells in odd columns. i need it to apply borders to every other
cell in a selection, regardless if it is even or odd.

Sub BotBorderOdd()
For Each cell In Selection
If Application.WorksheetFunction.Odd(cell.Column) = cell.Column
Then
oRange = oRange & "," & cell.Address
End If
Next cell
oRange = Mid(oRange, 2, Len(oRange) - 1)
Range(oRange).Select
With Selection.Borders(xlEdgeBottom)
.LineStyle = xlContinuous
.Weight = xlThin
.ColorIndex = xlAutomatic
End With
End Sub

Thanks for your help everyone!