diff --git a/powder-loader.scad b/powder-loader.scad
index d06f8eb..a0cf90b 100644
--- a/powder-loader.scad
+++ b/powder-loader.scad
@@ -12,8 +12,12 @@ border = 1;
 
 funnel_size = 1;
 
+part = 0;
+
 module _end_of_customizer() {}
 
+assert(part >= 0 && part <= 2);
+
 $fn = $preview?30:80;
 
 module overall_cylinder() {
@@ -29,7 +33,7 @@ module overall_cylinder() {
     }
 }
 
-*if($preview)
+if($preview && part == 0)
 color("#777")
 overall_cylinder();
 
@@ -71,8 +75,9 @@ module bottom_part() {
     }
 }
 
+if(part == 0 || part == 1)
 color("#dd08")
-*bottom();
+bottom();
 
 module top() {
     for(i = [0:5]) {
@@ -111,11 +116,12 @@ module top_part_hollow() {
     }
 }
 
+if(part == 0 || part == 2)
 color("#4d48")
 translate([0, 0, bottom_height])
 top();
 
-*if($preview)
+if($preview && part == 1)
 color("#f008")
 for(i = [0:5]) {
     rotate([0, 0, i/6*360 + 360 / 12])