diff --git a/public/index.html b/public/index.html
index e64053d..410c5ad 100644
--- a/public/index.html
+++ b/public/index.html
@@ -24,6 +24,24 @@
             background-color: rgb(0,0,16);
             display: inline-block;
         }
+
+        .slider-group > * {
+            margin-top: 1em;
+        }
+
+        .labelled-slider {
+            width: 100%;
+            display: flex;
+        }
+        .labelled-slider input[type=range] {
+            width: 100%;
+            flex-grow: 1;
+            align-self: center;
+        }
+        .labelled-slider span {
+            width: 5ex;
+        }
+
         @media screen and (max-width:430px) {
             html, body,            
             .tile {

diff --git a/public/index.html b/public/index.html
index e64053d..410c5ad 100644
--- a/public/index.html
+++ b/public/index.html
@@ -24,6 +24,24 @@
             background-color: rgb(0,0,16);
             display: inline-block;
         }
+
+        .slider-group > * {
+            margin-top: 1em;
+        }
+
+        .labelled-slider {
+            width: 100%;
+            display: flex;
+        }
+        .labelled-slider input[type=range] {
+            width: 100%;
+            flex-grow: 1;
+            align-self: center;
+        }
+        .labelled-slider span {
+            width: 5ex;
+        }
+
         @media screen and (max-width:430px) {
             html, body,            
             .tile {
diff --git a/src/Main.elm b/src/Main.elm
index 2dd3776..73451f4 100644
--- a/src/Main.elm
+++ b/src/Main.elm
@@ -1,6 +1,9 @@
 module Main exposing (..)
 
+import Browser
 import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
 import Svg exposing (..)
 import Svg.Attributes exposing (..)
 
@@ -33,27 +36,51 @@
     Point p.y -p.x
 
 
-tip line =
+tip tipHeight line =
     diff line.start line.end
         |> rotateMinus90Deg
-        |> scale (sqrt 3 / 6)
+        |> scale ((sqrt 3 / 6) * tipHeight)
         |> add (midpoint 0.5 line)
 
 
-kochDivide line =
-    [ Line line.start (midpoint (1 / 3) line)
-    , Line (midpoint (1 / 3) line) (tip line)
-    , Line (tip line) (midpoint (2 / 3) line)
-    , Line (midpoint (2 / 3) line) line.end
+kochMidPoints tipHeight gapWidth line =
+    [ line.start
+    , midpoint (0.5 - gapWidth / 2.0) line
+    , tip tipHeight line
+    , midpoint (0.5 + gapWidth / 2.0) line
+    , line.end
     ]
 
 
-kochIteration iterations lineList =
+pointListToLinesRec firstPoint remainingPoints lines =
+    case remainingPoints of
+        p :: ps ->
+            pointListToLinesRec p ps (Line firstPoint p :: lines)
+
+        [] ->
+            lines
+
+
+pointListToLines points =
+    case points of
+        p :: ps ->
+            pointListToLinesRec p ps []
+
+        [] ->
+            []
+
+
+kochDivide tipHeight gapWidth line =
+    line |> kochMidPoints tipHeight gapWidth |> pointListToLines
+
+
+kochIteration iterations model lineList =
     if iterations == 0 then
         lineList
 
     else
-        List.concatMap kochDivide lineList |> kochIteration (iterations - 1)
+        List.concatMap (kochDivide model.tipHeight model.gapWidth) lineList
+            |> kochIteration (iterations - 1) model
 
 
 lineToSvg : Line -> Svg.Svg msg
@@ -68,22 +95,109 @@
 
 
 baseHeight =
-    250
+    200
 
 
 startLine =
-    Line (Point 0 baseHeight) (Point 400 baseHeight)
+    Line (Point 50 baseHeight) (Point 350 baseHeight)
 
 
-main =
-    div [ class "tile" ]
+type alias Model =
+    { gapWidth : Float
+    , tipHeight : Float
+    , iterations : Float
+    }
+
+
+type alias LabelledSliderParameters =
+    { id : String
+    , label : String
+    , min : Float
+    , max : Float
+    , step : Float
+    }
+
+
+roundToPrecision : Int -> Float -> Float
+roundToPrecision precision number =
+    toFloat (round (number * toFloat (10 ^ precision))) / toFloat (10 ^ precision)
+
+
+labelledSlider params msg modelValue =
+    div [ Html.Attributes.class "labelled-slider" ]
+        [ label [ for params.id ] [ Html.text params.label ]
+        , input
+            [ Html.Attributes.id params.id
+            , Html.Attributes.type_ "range"
+            , Html.Attributes.min <| String.fromFloat params.min
+            , Html.Attributes.max <| String.fromFloat params.max
+            , Html.Attributes.step <| String.fromFloat params.step
+            , Html.Attributes.value <| String.fromFloat modelValue
+            , onInput msg
+            ]
+            []
+        , span [] [modelValue |> roundToPrecision 2 |> String.fromFloat |> Html.text]
+        ]
+
+
+view : Model -> Html Msg
+view model =
+    div [ Html.Attributes.class "tile" ]
         [ h2 [] [ Html.text "Koch" ]
         , div []
             [ svg
-                [ width "400px"
-                , height "400px"
+                [ Svg.Attributes.width "400px"
+                , Svg.Attributes.height "400px"
                 , Svg.Attributes.style "fill: none; stroke: purple; stroke-width: 1;"
                 ]
-                ([ startLine ] |> kochIteration 5 |> List.map lineToSvg)
+                ([ startLine ] |> kochIteration model.iterations model |> List.map lineToSvg)
+            ]
+        , div [ Html.Attributes.class "slider-group" ]
+            [ labelledSlider { id = "tipHeight", label = "Tip: ", min = -3, max = 3, step = 0.01 } ChangeTipHeight model.tipHeight
+            , labelledSlider { id = "gapWidth", label = "Gap: ", min = -3, max = 3, step = 0.01 } ChangeGapWidth model.gapWidth
+            , labelledSlider { id = "iterations", label = "Iterations: ", min = 0, max = 6, step = 1 } ChangeIterations model.iterations
             ]
         ]
+
+
+init : Model
+init =
+    { gapWidth = 1 / 3, tipHeight = 1, iterations = 5 }
+
+
+type Msg
+    = ChangeGapWidth String
+    | ChangeTipHeight String
+    | ChangeIterations String
+
+
+update : Msg -> Model -> Model
+update msg model =
+    case msg of
+        ChangeGapWidth newWidth ->
+            case String.toFloat newWidth of
+                Just w ->
+                    { model | gapWidth = w }
+
+                Nothing ->
+                    model
+
+        ChangeTipHeight newHeight ->
+            case String.toFloat newHeight of
+                Just h ->
+                    { model | tipHeight = h }
+
+                Nothing ->
+                    model
+
+        ChangeIterations newIterations ->
+            case String.toFloat newIterations of
+                Just i ->
+                    { model | iterations = i }
+
+                Nothing ->
+                    model
+
+
+main =
+    Browser.sandbox { view = view, update = update, init = init }