Lets create some more details. So, select the circle you first created, the one you see on the upper image, the small one. Extrude that circle to left by 10mm (when extruding left you need to input -10 in command line). Since you last used ExtrudeCrv command, we got left Both Sides to On, click on that text to turn it off, and make sure we still have no on Cap.
Now, we will create profile for our cap to finish off that extruded circle. Here you will find very handy to have Osnap options Cen and Mid to on. Using Sweep1 command, use that profile, and sweep along the extruded circle edge. Refer to image below:
Ok, we’ll create another circle, and again, it will be centered in the origin, so start Circle command, and type in 0,0 as center of circle, and confirm with enter and next type in 9 as our circle will be 9mm in diameter. Offset that circle by 0.2 to inside.
Extrude both circles with ExtrudeCrv command by 6mm left. That will again require inputing the negative value into the command line. This time, make the Cap=Yes, and Both sides still to No.
In this final step, we will make more details to the last part we created extruding the two circles. It is a good idea to isolate other parts, just to simplify modeling. You can either do that by hiding the objects, or placing them in hidden or locked layers.
Extrude that rounded rectangle just outside your tube object, and after that create a line in the top viewport on millimeter (1 boxin grid) from right corner.
Split the cylinder using Split command with the line we created (do that from top viewport). And, also, split the extruded rounded rectangle with that line too. You can delete bigger part of rounded rectangle, but leave both parts of the cylinder. Next, trim the bigger part of your cylinder with the smaller part of extruded rounded rectangle. (If it appears that your extruded rectangle part is acctually in two parts, just join them). Trim off the outer part of your cilinder. And then, delete the lower leftover…
In the upper image, there are two big surfaces and one that connects those two, and you can join those three using Join command. Next, from Right viewport, using ArrayPolar command copy that part 4 times around 0,0 as center.
Using Sweep2 command, fill the gap between the inner and outer cylinder and two polar arrayed parts.
Arraypolar that part (the yellow one in the upper image) like you did for those 4 parts, and join everything together, and unhide using Show command. And you are done!