A little about the river monitors:

During the Vietnam War, the US Navy's Brown Water Navy, operated its Monitors as part of their River Assault Flotilla One, which "initially" consisted of four River Assault Divisions (RAD); with RAD 91 containing 3 Monitors, RAD 92 having 2 Monitors, RAD 111 having 3 Monitors, and RAD 112 operating 2 Monitors.
The Vietnam Monitors were divided into two programs; program 4 would consist of the 40mm gun Monitors, while the later program 5 would entail the eight Monitor (H) Howitzer versions, and the six Monitor (F) Flamethrower models. All of the Monitors were converted from World War II 56' long all steel Landing Craft Mechanized (LCMs) Mk 6's.[9] When completed, they were 60' long, 17' wide, with a draft of 31⁄2', had two screws driven by two Gray Marine model 64NH9 diesel engines, could do 8.5 knots and were manned by usually 11 or more crewmen. They usually carried about ten tons of armor.
Source:
https://en.wikipedia.org/wiki/River_monitorBeam: 17.5 feet
Draft: 3.5 feet
Propulsion: 2 Gray Marine 64HN9 225 hp, 2 shafts
Speed: 8 kts Range: Crew: 11
Weapons: Mk I Mod 0 MON: 1 40mm L/60 Bofors, 1 .50 AN/M-2HB mg (co-axial), 3 20mm Mk 16 or 2 20mm Mk 16 and 1 40mm Mk 19 grenade launcher, 2 Mk 21 7.62mm mg, 1 81mm Mk 2 Mod 0 mortar.
Source:
http://www.warboats.org/monitor.htmI have decided to go for the Mk1 with the 40mm autocannon. It was ca 17 meters long, so in scale 1:50 it will be about 34 cm long, suited for 28mm gaming.

The tools of the trade. As you can see, I decided to use an empty roll of toilet paper in the project. Hope this is not considered cheating...


Carving up the box of contact lenses and assembling the hull. This is the bottom part of the hull.

The top of the hull with the mortar pit.