Tips For Improving Tank Models Filling lower hull holes. Filling in the sponson gap between the upper & lower hull.


Many model tank kits suffer from one or both of the following problems:
1. The tank's lower hull was molded to be 'motorized', which means there are holes in the sides for axles to pass through from a gear-box inside the hull and there are holes in the bottom of the hull where the gear-box and motor are attached by screws, and there's usually another hole for an on/off switch.

2. The underside of the sponson area is left open (I.E. There's a gaping hole between the upper & lower hull where the upper hull overhangs the lower hull).

Both these problems are easily fixed, and will improve the overall appearance of your tank model (even in cases where the underside of your finished model will not be seen, these quick fixes are a good idea just because they improve the overall realism of the model).


The following simple fix can be applied to any unnecessary, or unwanted hole in a model tank hull (or any other model for that matter).

STEP 1 - On the inside of the model, cover the hole or holes with thin sheet styrene plastic. By covering the holes from inside the hull (or other kit part) you reduce the amount of putty needed to fill the holes (next step)

STEP 2 - Fill each hole with modeling putty (Green Stuff, etc.). Let the putty dry. It will shrink & leave a 'dent' near the center. Sand the putty, then apply more putty to fill in the shrinkage / dent. Repeat as needed until you have a smooth flat surface.

EXAMPLE: See Photos Below. This is a Tamiya M5A1 Stuart kit. The lower hull was created using older molds for the M3 Tank series which were originally designed to include a motor & gear-box.


SciFi Dragon Models

SciFi Dragon Models

SciFi Dragon Models



The term 'sponson' refers to that part of a tank's upper hull that overhangs the lower hull and extends out over the track & suspension assemblies. Even some of the best model tank kits fail to fill in the gap between the upper and lower hull caused by this overhang. However, this gap is a glaring mistake and, depending on how you display your finished model, the open area just above the top of the tracks may be visible & will ruin the realism of your model. This flaw in the kit design can easily be fixed.

STEP 1: BEFORE you begin assembling the kit, TEST FIT (no glue!) the upper and lower hull parts

STEP 2: Use a rubber-band (lengthwise across the hull) to hold the upper & lower hull parts together. Insert a thin piece of cardboard or very stiff paper into the gap where the upper hull overhangs the lower hull.

STEP 3: Trace the outline of the upper hull onto the piece of cardboard (or paper) to get the length, width, and shape of the sponson gap.

STEP 4: Cut out the paper outline of the sponson gap (cut INSIDE the pencil lines) and use the cut-out as a template. Place your template onto a thin piece of styrene plastic sheet (no more than 020 thick) and trace the shape of the sponson gap.

STEP 5: Cut out two (2) plastic sponson gap covers (one for each side of the tank). Test fit each cover. Trim or sand the covers as needed to get a clean fit inside the gap between the upper and lower hull.

STEP 6: Attach (glue) the sponson cover to the underside of the upper hull part, just inside the hull and flush with the bottom of the upper hull. IF the particular kit has enough empty space inside, reinforce the sponson cover by gluing a square or rectangular 'rod' between the side of the hull and the top of the sponson cover (rod has to be in contact with both surfaces).

EXAMPLE: See Photos Below - Installing sponson covers on an M4A2 Sherman. This procedure applies to any Tamiya M4 series Sherman tank or similar tank:


SciFi Dragon Models
The Tamiya kit has a gap between the upper and lower hull parts, indicated in the photo (LEFT) by the areas covered in white sheet styrene plastic.
Filling the gap between the hull parts adds to the realism of your model, since no real tank has an opening between the upper & lower hull areas.


SciFi Dragon Models
The photo (RIGHT) shows the finished M4A2 Sherman model. Once painted and weathered, the covered sponson areas look far more realistic than the gaps in the unmodified kit would have looked.


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