In this design, there are overhangs for that we need supports in the of printing. So to avoid supports we will use splitting.

Step 1: Drag a hole box and place like half of the design should be inside the cylinder.

Step 2: Duplicate the hole cylinder.

Step 3: Drag the duplicate box to the other half of the design.

Step 4: Using Shift key select the inner design and duplicate it.

Step 5: Now select one box with already selected design using shift key. Group them.

Step 6: Now select other box with the design and group them.

 As you can see, the design is split into two.

Now change the orientation to print the design without supports.