Well I\'m hardly the man to be giving out sculpting advice, but I\'ve tried to sculpt a few Ultras symbols before, so I\'ll be happy to let you know what I\'ve found out.
Personally I tend to start off with a square, roughly the size you want the symbol to be.
It\'s probably not quite the same scale you\'re thinking of, but these are a couple of examples of my sculpts.
Basically I just rolled out some GS/Milliput (I tend to use a 50/50mix of Greenstuff & Milliput, but then I\'m a bit plain weird that way) & cut out a square.
Then you can use the top corners of the square to be the top corners of the flat part of the symbol.
Cut a small line down fom the middle of the top edge & press the handle of your brush, or a staw or something to make the hole in the middle.
I use the basic GW sculpty-poker, but you can use knives or proper tools or whatever you normally use, & then just cut out the curved bottom corners of the square, leaving you with a more traditional \"U\" shape.
Using the same tools snip the little triangles out from underneath the two upper corners to make the fancy little serif ends of the U symbol, & bam, you\'ve got a pretty accurate Ulras symbol.
Like I said, I\'m hardly profficient or anything & I\'d hardly say I\'m that experienced either, but that\'s how I do it (albeit very badly explained

)
Best o\' luck.