Hello! Before I begin explaining, please note that I reversed my progress many times, as the chamfering was hard to work with, but was needed to help me do this thing. With that out of the way, let's begin! Also, note that this will be stationary, you cannot move this like an action figure. If you want, you could try to separate the arms, legs, and head, and add parts to make it an action figure.

Step 1: Step 1. Make a Sketch!

I made a sketch on the XZ axis. I made a mistake here that I would regret later... Please, I beg of you, make each leg, arm, and chest/head its own body! Trust me, this will be relevent later.

I made the chest/legs 60 mm long, and 90 mm tall. the head will be half of a head, (We will be revolving later!) and make it look like a roblox character's default head. Make it to your liking, but make it 10 mm tall.

Each arm is 20 mm wide, and 45 mm tall.

Step 2: Step 2: E X P a N D (Symmetrically!)

For this, go into CREATE > EXPAND, expand the bodies upwards 10 mm symmetrically, (Not the head, leave that alone for a bit longer!)

That's the whole step...

Step 3: Revolve the Head!

Revolve the Head over the Z-axis on the head, the long line,and revolve it, (CREATE > REVOLVE) Now, you have a head. If it doesn't look good enough for you, go and change it and come back here.

Step 4: Step 4: Begin Chamfering!

For this step, make a line along the ends of the arms, legs, and chest, (Only one line! I made the mistake of making three on some body parts, and I did not have a good time because of it!) For the bottom legs, hide the head's body, as if you do not, the line will not work correctly. Trust me, I did not do this, as because of it, it was impossible to chamfer the backs of the legs. Next, select the chamfer tool, (MODIFY > CHAMFER) and chamfer 1 mm on each side and body part edge.

Step 5: Make the Default Face!

Make an offset plane on the Z-axis, (CONSTRUCT > OFFSET PLANE) and then get an image of the default Roblox face from google. Warning, be careful! Instead of downloading, which may give you problems, use the Snipping Tool (Not in Fusion 360, in the desktop search bar, if on Windows 10.) And get the image. Insert the image into the offset plane, (INSERT > ATTACHED CANVAS) and center it on the head. After this, and then make a sketch on the Z-axis, (SKETCH > CREATE SKETCH) And use the 3-point Arc, (SKETCH > 3-POINT ARC) to make the eyes and mouth outline. Then, extrude all the way up the head, and you now have a face! (CREATE > EXTRUDE)

Step 6: End!

By this point, the Roblox character should be like this. If you want, you could make the face closer to the top of the head, to see it better, but this is optional. It is recommended however, if you plan on printing it small.