Click Modify. In the Dimension Style Manager, Symbols and Arrows tab, under Arrowheads, select User Arrow from the First arrowhead list. In the Select Custom Arrow Block dialog box, enter the name of the block that you want to use as an arrowhead. Click OK.
There aren’t many things you can do to make your dimensions look different from those
of every other AutoCAD user, but you can create a custom arrowhead. I personally like
the traditional open arrowhead that I used when drawing by hand. In AutoCAD, I reproduce
that venerable shape with a line segment and two large radius arcs. If
you’re as nostalgic as I am for the arrowheads of yore, do this:
1. On layer 0, draw an arrowhead one unit long and pointing to the right.
2. Define a block with the arrowhead you just drew, using the arrow point as the inser-
tion point.
3. Select User Arrow from the bottom of the First list in the Arrowheads section of the
Symbols And Arrows tab of the Modify Dimension Style dialog box.
4. Select your arrowhead block by name. If you want to use your custom arrowhead for
leaders, you have to specify that by selecting it from the list of possible arrowheads in
the Leader pane of the Symbols and Arrows tab.