Hi Don, is it possible for you to include the 3DM model file along with your post so that others can use your actual geometry to work with to make suggestions? That helps a lot - otherwise people are going to have to do the work to create the other parts of your model in order to show you some examples. And possibly the things they create may be slightly different than what you have in shape or topology or whatever.

It looks like Mike has some good recommendations for you above - probably the easiest thing to try is the Blend tool. Normally the blend tool is for making a smooth surface that connects 2 surfaces that have some space separating them, see here:
http://moi3d.com/2.0/docs/moi_command_reference7.htm#blend

But you can also use it when you've got 2 edges that touch each other just at their ends and have an open area in between them, so if you've got 2 edges at the top of something like this:


You can select both the edges there (note - for this kind of a Blend you've got to select the edge of the surface - if you've got any curve objects that were used to build the surfaces hide those to get them out of the way so that you can select the surface edge as the blend input), and then run Construct > Blend to build a smooth piece between them:



- Michael

Thanks for the pointers, but I just can't get exactly what I want. I am so used of precision drawing that getting something 'close' does not feel right. I will need to experiment further. I have not had much time to practice with MoI for the last few months so I am a bit rusty.

Michael, I know it is good to upload one's models for others to look, but I don't always like to post my models on the public forum as one can easily lose them to the masses.

Hi Don, you don't necessarily have to post the entire model - for example in this case just those top side surfaces of the handle that you're trying to place the cap on would work.

Without any kind of geometry to work with I'm afraid it is much more difficult to give very good suggestions.

- Michael