Hi timo, sort of melty blobular shapes can be a difficult because they often don't suggest a really clear curve structure to draw initially.
But there some different ways that you could approach it.
One way is to initially imagine the shape is a more straight rounded thing and then create that by drawing a profile and revolving it, and then turning on surface control points (use Edit > Separate if your revolve is a solid with an end cap joined on, or turn off end capping in revolve so you get just a single unjoined surface that can have points turned on) and then move the sections around to deform it.
There's a tutorial that lyes did on this kind of technique here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=1514.1
The thing that tends to be nice about that method is that revolved shapes have a nicely formed tip area that won't have any kind of bunching in it.
Then a different way than that is to draw guide curves in and use Network or Sweep to create your surface directly in place.
Here's an example using Sweep:
http://moi3d.com/forum/index.php?webtag=MOI&msg=415.2
The issue with this method tends to be getting the tip shaped well. When the various profile curves come together into a single point, if the surrounding shapes are fairly different in lengths or proportions it is easy for there to be a kind of bunching when they compress down to a single point and that can leave some kinds of artifacts in the tip shape.
One thing that can help with that with Network is to include a small circle as a section curve nearby the tip. Since a circle is a nice symmetrical shape, putting in a circle before the tips actually come to their shared point tends to make for a better shaped tip that is more evenly proportioned where the points come together.
See the attachments in these threads for an example of that kind of Network with a circle at the tip thing:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3550.1
http://moi3d.com/forum/index.php?webtag=MOI&msg=3623.14
Then even a different strategy yet is to temporarily ignore the tip and build a shape shape using whatever surface tool you want but that comes to a flat plane at the end. Then you can produce roundness at the tip by filleting that edge. You can fillet it with a large radius until most of the end plane is eaten away and also you can put in a slightly rounded end surface before filleting if you don't want any planar bit in the bottom at all.
Here's some examples that are kind of similar to that, where there are 2 curved sheets that then are filleted where they cross to produce the full smooth shape:
http://moi3d.com/forum/index.php?webtag=MOI&msg=2164.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=2164.4
Sometimes that method can work well if the tip area is a little bit broader and has somewhat of a distinct shape of its own and then a kind of transition area where it blends to the main body shape, but not quite as much when the tip is more like the main body just evaporating away.
Or also similar to that is modeling just the tip as a little revolved piece and then using blend to connect it with the main piece:
http://moi3d.com/forum/index.php?webtag=MOI&msg=2221.5
That can sometimes be hard to control though, if you don't have a very even spacing the blend will kind of make an "S" shape.
There is not always just one answer, you can try some of these methods and see which one you like. Sometimes even different styles of rounded-ness can lend themselves to slightly different methods.
- Michael