Well, like Macgayver did on the midmast of the "Unicorn", I prolonged the frontmast the same way, as I also do on some of my standard 3940's:
I use the old tanbrown knifethrower-disc (comes in a set from the '80s) as mastplatform. As base to put it on, I use a standard ship's crownest's baseplate: the sides are sawn off. In the middle of the knifethrower's disc I drill a hole. The thingies to hold the klicky-acrobat on the disc are sawn off as well, and the holes where the knifes are to be put in are a bit enlarged and rounded to hold riggings for the uppermast.
Then I glue the disc (with or without some paintwork) on the crownest-basis. The crownest gets a hole in the center and is placed on a mast as usual. Then I take a stadard aft-mast and make it a bit shorter. I glue a piece of a mastspar inside the uppermast's back, the underside of this spar (or another long small piece of plastic or wood can be used as well) sticks some cm's (inches) out off the underside of the mastprolongation, and is then inserted through the disc with crownest-basis into the upperpart of the standard lower mast. The standard lower mast is open at the back, and it's top is closed only about half an inch, so you saw off about that much of the standardmast to insert the custom-uppermast...
On top of the mastprolongation you put a standard masttop or crownest, and then add the upper riggings. For this I use 3-way riggings, thus from a ship's aft mast or from a schooner (= sloop/cutter
) The riggings are shortened on the bottom by sawing off the attachment-points (used normally to attach the riggings to a ship's hull), so that you have pointy but sturdy "strings" to put throught the knife-holes of the disc.
If done well, all this is quite sturdy and not wobly or anything. In case the uppermast is a bit wobly, then you just fix that with some additional ropes.
I hope this explanation makes some sense?
