The Skirt Assembly

First step is to separate all of the parts from the sheets they were machined from, remove the tabs and flash, if any.

The skirt ribs were assembled from two pieces of .25 in thick styrene. However, I can no longer get .25 thick styrene so ribs are now printed on my 3D printer.
Instead of 24 pieces to glue together there are now just 12 complete ribs ready to use.
The picture on the above right compares a CNC cut & glued rib (upper, you can see the joint line) to a 3D printed rib (lower). While you can see the 'grain' on the 3D print  you don't need to do any additional finishing, those sides get glued onto the skirt body and are hidden. The bottom of the rib is against the glass bed of the printer and comes out smooth!

As with the frame parts, the front of the Skirt Base, also known as
Ring 0, is marked with a locator hole. The hole will be covered up
by the riser that goes in the slot above it, but will be visible from the
underside of the assembled skirt.

The other (partially drilled) holes mark the locations for the
ribs to be placed, at the end of the assembly process. (see below)

Actual assembly starts with the skirt base.

familiarize yourself with the parts. do a trial fit of the risers
into the skirt base (ring 0)

put the skirt bottom in place verify the fit as well

note that riser c has to be chamfered. this can be done
before or after you glue things in place. it's up to you.

right: edges of riser after chamfering. if you want a
stronger bond you can glue pieces of scrap styrene
to the edge of the angled part of the riser.

you have a choice depending on how you like to work. tape the
risers so that the edge is flush with the skirt bottom. you can do
it before or after you apply the glue.

tape all of the risers so they stay in alignment

when the glue sets check the alignment. make sure the risers are
square and flush with the edge of the skirt bottom.
reassemble to the skirt base and glue in place.

only glue the curved side piece to the 3 center risers.
do not glue to
the end risers.
those ends will be glued when you glue the straight
side pieces in place. 

all of the .040 pieces have been left slightly over length so
they can be trimmed to a precise fit. trim the end of the
curved piece and the straight side piece it mates with.

I find it easy to trim pieces like this with a diagonal cutter.

glue the straight side piece in place and let the glue set.

trial fit the cone shaped side. note the pencil mark for the center.
like the straight side piece, only glue to the 3 center ribs. leave the
ends loose to fit and glue with the angled side pieces.

first trail fit the angled side pieces. trim the ends as needed so
that everything comes together neatly.
right: once you are happy with the fit, glue the angled sides
to the risers and glue the miter joints on the end.

Once the glue to set on the skirt you can add the skirt ribs.

start in the center and glue the two center ribs using the location
marks in the skirt base. (see above). I didn't put location marks
for the tops of the ribs. there are already too many riser holes that
you are going to have to fill in. note the pencil marks as guides

The end ribs line up with the miter joint between the curved and
angled piece. once the end rib is in place, use the location marks
to place the bottom of the remaining ribs. measure the top spacing.
make it the same distance apart as the center ribs.
it's easy to get wrong. so put in a pencil mark for that space too.

Congratulations, you've got a completed skirt for your R2!

revised 04/08/16