Create polygon from click

Hello,

I am trying to figure out some code. I have a TIN basemap and a raster file as a maximum height over the TIN. The idea is I need to click a random point on the TIN, have it bring up a window where I can enter length, width, and angle. This would then create a polygon. I then need to find the volume of that polygon made up of the TIN basemap, raster topsurface, length and width. The angle is to take the different heights of the TIN into account when calculating the volume.

Thanks!