“…2. (a) SLS made polyamide-based models of heat exchanger for a Pratt & Whitney PW6000 engine [13] (b) Resin shell + slurry filling for wax making die [26] (c) Patterns fabricated by direct and indirect RT routes for sand and investment casting [23] : R-resin, W-wax, PU-polyurethane, RTV-a rubber, S-solid, VCvacuum casting, WIM-wax injection moulding (d) Assembled core and mould fabricated by 3DP [35] 2.1 Rapid tooling-3D printing of prototype, pattern, core box and wax injection mould A number of direct routes using 3D printing methods such as FDM, LOM, SLA, SLS, etc., as well as indirect routes (3D printing methods coupled with secondary or soft-tooling processes like vacuum casting), are available for rapid fabrication of a prototype, pattern, core box, etc. for the first step in the casting process [8][9][10][11][12][13][14][15][16][17][18][19][20] . This is also called rapid tooling (RT).…”