When I built my first matchstick model I used craft knife and sandpaper result sore fingers?
Later used the following cutters.

cutter cutter-2

I have mine adjusted to give half and one third sizes and one variable if I need quite a few of one size
The other cutter is usefull for repeated angle cuts

After building sections cutting/trimming to size I usually use a fretsaw

bender
Bending matches I recently aquired a bandsaw and built the bender
I soak matches in hot water for half an hour then clamp them,
leave for a few hours,you can then tweek them with gentle pressure with your fingers to suit.

I have a sheet of dense cork about an inch thick ideal to accept pins.

pattern
Cut a pattern to shape wax the edges and use greaseproof paper
position and glue matches.

chines

When building my boat I screwed some blocks to some wood and clamped the keel
which left both hands free to position and glue chines

support

If you have unusual gaps to fill leave a largish space glue two or three matches together
a lot easier to hold and shape to fit.

All photographs Copyright Fred Fox.