1.     Remove The Moulded Representation. Check The Size Of The Replacement First, Not All Mouldings Are Scale And Different Manufacturers Have Different Interpretations. 

2.     To Do This Fit A 3mm Drill To A Pin Vice And Drill A Series Of Almost Linking Holes Around The Inner Edge. (See Drawing).

3.     Then Run A Scalpel Around The Holes And Push The Centre Out. Do Not Apply Too Much Pressure, As On Thin Plastic Shells There Is A Risk Of Distortion. (See Drawing).

4.     Then Clean The Resultant Ragged Edge Up With A Scalpel And A Half Round File. If The Replacement Grill Is The Same Size As The Moulded Original Go Up To The Rim, But Do Not Remove The Rim. (See Drawing).

5.     Use The Etched Grille To Measure The Progress From Time To Time, As It Is Essential Not To Remove Too Much Material.

6.     REMOVE MATERIAL SLOWLY AND CHECK REGULARLY. Only Go To The Rim, Leave A Rim To Attach The Etching Too.

7.     When You Are Satisfied With The Fit, Pare Down Any Raised Rim Flush With The Shell To Give A Bonding Point For The New Grille.  (For Most Fan Grilles You Are Fitting Them To A Curved Roof, To Curve The Etching Place On The Ball Of Your Thumb And Gently Press The Curve In To Match The Roof Profile.

8.     Apply Cyano Adhesive To The Bodyshell And Fit The Grille Into Place Ensuring That It Is Correctly Positioned.  

9.     For Added Depth, Fans Should Be Added Per The Diagram. Adding Depth To Them Depends On Your Requirements And Choice Of Prototype.