I traced the outline of the board (CrazyFly Raptor) onto butchers paper and cut it out. This made it an easy job to rescale the baord size by placing folds along the centre lines of the paper. I took 2cm off the length and 3cm off the width.
Remember to account for the width of the rails (10mm) and reduce the board core size accordingly.
Cut out the fin slots to get them ready for filling with epoxy. Firstly cover the top and bottom of the opening for the fins with masking tape. Then cut the tape away from the top side. This will keep the resin inside the fin support area and make removing the excess resin that will inevitably get on the board as easy as peeling the tape away.
I used 1/4" stainless steel T-nuts for the footstrap inserts and filled around them with 5 minute Araldite cause I didn't want to have to wait for too long to get things moving along.
The holes for these are made all the way through the board and then filled with resin. I just used a softdrink bottle top to trace out the hole size. I've made the distance between the instep bolts 18" and the spacing between the bolts on each foot are 6.25". Because I stand with my feet splayed out like a duck I've put more angle on each footpad. I put the instep bolt 3/8" above the centerline and the outside one 1" below. The other boards I've looked at have the instep bolt on the centreline.
You want the top of the t-nuts to be just below the surface of the board and you want the bolt when screwed all the way(through the footstaps and pads to not damage the setting by cracking the resin below the nut. To get the t-nut sitting in exactly the right spot I used the following approach - I thinned out a Klegecell offcut so that when the screw was passed through it into the t-nut and flush to the surface of the klegecell, the threaded end of the screw poked out a millimeter or so. The kelegcell piece cahn then be sat across the hole to make sure the t-nut is in exactly the right spot. The hole around the t-nut can then be filled with 5 minute epoxy and the screw/nut connected to the klegecell can be inserted into the epoxy. Leaving the screw in prevents epoxy getting inside the thread and making it difficult if not impossible to screw the bolt in.
Although I am probably going to use 12mm bolts in the final board, I worked with 16mm bolts so that I could make sure that there is enough of a gap between the end of the screw and the epoxy in the insert to avoid damage from over tightening or using long screws later.
Make sure to work the t-nut up and down to avoid any air bubbles being opened in the epoxy when you insert it. If air bubbles do open up it would be wise to grind the resin out from around the bubbles and re-fill them.
In the photo below I placed some baking paper under the klegecell but that was a bad move as it creased and then caused a crease to be set into the top surface of the insert. Its also not necessary as the klegecell is easy just to sand back once everything is set. Afterwards I topped it up with 5 more 5 min epoxy and sanded it flush with 50 grit sandpaper.
Filling around the edges of the top deck
As I understand it, fibre glass doesn't deal well with sharp corners and so its necessary to fill the sharp corener that exists between the edge of the top deck and the lower deck.