I'm new to rodbuilding and am on my second rod, a 9 wt. I was considering using a fuji 16mm skeleton and a 7/8" celluloid pen blank for the insert. My question is " Is this reel seat setup strong enough for a flyrod that is going to be used for saltwater? And mainly, how durable is the celluliod pen blank material?"

Dan,
the barrel of a reel seat doesn't take a lot of strain, if any. The bulk of any strain on a reel seat is on the hoods when locking down a reel. Provided that you have your mounting done well, it really comes down to what will be cosmetically appealing after many years, rather than the strength of the insert. Personally, I don't see any reason why a general pen blank won't look good after time.

Dan , if you take a look thru the photos under the handles you will see some fly handles with incerts that aren't even connected in the center, the two halfs are tapered to the blank in the center . As Mick stated , if you have a strong bond of the skeliton and hoods to the incert pieces ( good prep , scuff and fit ) with a quality adheasive epoxy ( Rod Bond ) you will have no problems . You can get quite creative with the choices of incerts as you will see in the photos .
Have Fun , John NERBs .

Got Fish ?

Dan,
What is the diameter of the blank where your reel seat will be located? If you need to center bore a large hole, it can't hurt to epoxy in a piece of thin walled brass tubing for added strength. I think the wall thickness is only .014", so it won't take up much space.
I completely agree with the above statements concerning normal stress on the seat while fishing. It's the other non - fishing times when it could take an unexpected whack. A little prevention could avoid a bigger problem later.

i agree with joe emig. i have played with the acrylics and used some for reel seats. the acrylic is ok,but it is even better when cast in the polyester acrylic. in my opinion the polyester acrylic is tougher than the acrylic alone. the brass tube inside does give a little strength which may not be necessary, but is a simple step to add.

good luck with the acrylic it is fun to play with