Here is a basic two-train system.
(14) Standard gauge straight
(32) Standard gauge curve, 72in
(2) Standard gauge 90° cross
Total of 48 items
A few switches and the layout becomes a cloverleaf.
(13) Standard gauge straight
(32) Standard gauge curve, 72in
(4) Standard gauge 90° cross
(3) Standard gauge cut straight
(2) Standard gauge Lionel #210L turnout
(2) Standard gauge curve, 42in
(2) Standard gauge Lionel #210R turnout
(2) Standard gauge MTH St-72 lefthand turnout
(2) Standard gauge cut St-42 curve
Total of 62 items
(15) Standard gauge straight
(28) Standard gauge curve, 72in
(4) Standard gauge 90° cross
(5) Standard gauge cut straight
(3) Standard gauge Lionel #210L turnout
(2) Standard gauge curve, 42in
(3) Standard gauge Lionel #210R turnout
(4) Standard gauge MTH St-72 lefthand turnout
(2) Standard gauge cut St-42 curve
(2) Standard gauge MTH St-72 righthand turnout
Total of 68 items
The inside spur line is great for trolleys.
(18) Standard gauge straight
(28) Standard gauge curve, 72in
(6) Standard gauge 90° cross
(8) Standard gauge cut straight
(3) Standard gauge Lionel #210L turnout
(10) Standard gauge curve, 42in
(3) Standard gauge Lionel #210R turnout
(4) Standard gauge MTH St-72 lefthand turnout
(2) Standard gauge cut St-42 curve
(2) Standard gauge MTH St-72 righthand turnout
(2) Standard gauge medium-straight
(2) Standard gauge #25 illuminated bumper
Total of 88 items
(23) Standard gauge straight
(28) Standard gauge curve, 72in
(8) Standard gauge 90° cross
(11) Standard gauge cut straight
(2) Standard gauge Lionel #210L turnout
(18) Standard gauge curve, 42in
(2) Standard gauge Lionel #210R turnout
(4) Standard gauge MTH St-72 lefthand turnout
(2) Standard gauge cut St-42 curve
(2) Standard gauge MTH St-72 righthand turnout
(4) Standard gauge medium-straight
(4) Standard gauge #25 illuminated bumper
Total of 108 items
(28) Standard gauge straight
(16) Standard gauge curve, 72in
(4) Standard gauge Lionel #210R turnout
(8) Standard gauge curve, 42in
(2) Standard gauge half-straight
Total of 58 items
(33) Standard gauge straight
(16) Standard gauge curve, 72in
(8) Standard gauge Lionel #210R turnout
(16) Standard gauge curve, 42in
(4) Standard gauge half-straight
(4) Standard gauge cut straight
Total of 81 items