I agree with what George says and it'll be very close!!!!
George has been particularly helpful with this, but in this instance I'm going to have to let you down, guys. I thought you might enjoy the 'toolpath map' of the inlay hollowing. Bear in mind that the tool is 0.8mm in diameter, yet the scale of the inlay makes it look large and clumsy:
That might impress upon you just how limited I am by the scale of these inlays - the max width is 12.4mm (dictated by the diameter of the pen barrel) and the smallest cut width I can make is just about 1mm (dictated by the end mill). Adding a mast, for instance, would require that I cut a path approx 0.5mm wide (too thin!) and fill it with a sliver of inlay about 0.5mm by about 25mm by about 7.5mm deep! Just not possible without better tooling, I'm afraid!