How to build seats:
I purchased my Eliminator with bad seats.I took apart the old seats and traced the old wood frames onto new plywood and cut it out.After cutting and cleaning up all the pieces I screwed and stapled all of them together forming new seat frames.I finished them with fiberglass reinforcements at the seams and coated them with resin.My old seat covering was not that bad so I reused it.
If you dont have old seats look at pics of other boats.Design and build frames to fit your boat and take them to an upholstery shop and have them covered.
I dont like to pay people to do things for me that I can do myself but if you have the money take the boat to a upholstery shop and have them do the whole job.