Hi everyone
I’m new in sketchup community and also in sketchup software so… my question is how to make an inflatable objects
and separate all the objects for high format printing to finally stitch/sew them together for one enormous inflatable gate/tent
like this one for example.
Do I need some special plugin for that?

Here is a quick sample done with the Follow Me tool and Intersect Faces in 2017. Dimensions are not the same as yours but you can get the picture. There are plugins that you can then use to add the pictures and etc. (cannot think of the names of them right now - have to leave for a while but if no one else responds, I will try to look them up later.)

Start with something less challenging like the little feet
Make two lines representing the inner and outer circumferences of the “Inner tubes” (I chose 32” inside and 16” more to the outside) Then build a square box up (16” x 16”) off the two lines and bisect it w/ a couple of diagonals. The entity info box tells me that the diagonal from corner to center is 11 5/16”.
Now make three circles to intersect the diagonals and fill the box, the info box tells me my radius is 8” as expected. select the field (blue) between the circles
Use the follow me to extrude the lowest quadrant of the circle (by starting clean with lines you assure that the facets of the inner and outer circles are in alignment)
Now delete the intersecting elements as shown until you can triple click on the outer circle and select only it and the circumference will show up in the entity info box here the outer circle shows up as 28’2” and triple clicking the inner circle shows that is 23’ 1-7/8”
By shift clicking the upper arches I can see that one quarter of the circumference of my 16” diam tube is 1’ ½” so we need an inner gusset that is 23’ 1-7/8” long by 1’ ½” wide plus allowance for seams and another that is 28’2” long by 1’ ½” wide plus allowance for seams. Now we just need the top and bottom.
Draw a line that intersects the diagonals where they intersect the arches and extends to a point over the center of the circle. This gives me the inner radius of the circle (here its 2’ 10-5/16”) and adding the distance between the two intersections gives me the outer radius (3’ 9-11/16”) plus seam allowance. Once inflated my inner radius will be approximately 28” and the outer radius will be approximately 54” because the inner gusset will bow towards the center and the outer one will bow away from the center.
So I just slide over a foot and create the big donuts to represent my top and bottom with those inner and outer radii and then see how I can efficiently lay them out on fabric blanks to minimize waste and we are ready to apply the graphics and cut them out and sew & glue them together.
Hope this helps and that you can take it from here to make the other shapes you are looking for.
M