diff --git a/src/main.cpp b/src/main.cpp
index bf38495..8a26f07 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,5 +1,5 @@
 
-#include "reactor/reactor.hpp"
+#include "reactor/builder.hpp"
 #include "reactor/control/control_rod.hpp"
 #include "reactor/fuel/fuel_rod.hpp"
 #include "reactor/coolant/pipe.hpp"
@@ -18,19 +18,20 @@ int main()
 	nodelay(stdscr, TRUE);
 	curs_set(0);
 	
-	sim::reactor::reactor<2, 2> reactor({
-		new sim::reactor::fuel::fuel_rod(100, 400),		new sim::reactor::fuel::fuel_rod(100, 400),
-		new sim::reactor::control::control_rod(1000),	new sim::reactor::coolant::pipe()
-	});
-
-	((sim::reactor::control::control_rod*)reactor.rods[0][1])->set_reactivity(0.99);
+	sim::reactor::reactor<5, 5> reactor = sim::reactor::builder<5, 5>(
+		sim::reactor::fuel::fuel_rod(100, 400),
+		sim::reactor::control::control_rod(1000),
+		sim::reactor::coolant::pipe(), {
+			"  P  ",
+			" FCF ",
+			"PCPCP",
+			" FCF ",
+			"  P  "
+		});
 
 	for(;;)
 	{
-		for(int i = 0; i < 1e3; i++)
-		{
-			reactor.update(1e-3);
-		}
+		reactor.update(1);
 
 		erase();
 		display::draw_text(1, 0, "Reactor Core:");
diff --git a/src/reactor/builder.hpp b/src/reactor/builder.hpp
new file mode 100644
index 0000000..64f1e6a
--- /dev/null
+++ b/src/reactor/builder.hpp
@@ -0,0 +1,46 @@
+
+#pragma once
+
+#include "rod.hpp"
+#include "fuel/fuel_rod.hpp"
+#include "control/control_rod.hpp"
+#include "coolant/pipe.hpp"
+#include "reactor.hpp"
+
+namespace sim::reactor
+{
+
+template <int W, int H>
+reactor<W, H> builder(fuel::fuel_rod fr, control::control_rod cr, coolant::pipe p, std::array<const char*, H> lines)
+{
+	std::array<rod*, W * H> arr;
+	
+	for(int y = 0; y < H; y++)
+	for(int x = 0; x < W; x++)
+	{
+		char c = lines[y][x];
+		rod* r;
+
+		switch(c)
+		{
+		case 'F':
+			r = new fuel::fuel_rod(fr);
+			break;
+		case 'C':
+			r = new control::control_rod(cr);
+			break;
+		case 'P':
+			r = new coolant::pipe(p);
+			break;
+		default:
+			r = new rod();
+		}
+
+		arr[y * W + x] = r;
+	}
+
+	return reactor<W, H>(arr);
+}
+
+};
+
diff --git a/src/reactor/control/control_rod.cpp b/src/reactor/control/control_rod.cpp
index 774944a..3562009 100644
--- a/src/reactor/control/control_rod.cpp
+++ b/src/reactor/control/control_rod.cpp
@@ -8,11 +8,6 @@ control_rod::control_rod(double limit)
 	this->limit = limit;
 }
 
-const char* control_rod::get_name() const
-{
-	return "Control Rod";
-}
-
 void control_rod::display(std::ostream& o) const
 {
 	o << "Inserted: " << (inserted * 100) << "%\n";
diff --git a/src/reactor/control/control_rod.hpp b/src/reactor/control/control_rod.hpp
index b1b5c68..72f8d67 100644
--- a/src/reactor/control/control_rod.hpp
+++ b/src/reactor/control/control_rod.hpp
@@ -12,10 +12,12 @@ class control_rod : public sim::reactor::rod
 	double absorbed = 0;
 	double limit;
 	
-	virtual const char* get_name() const;
 	virtual double get_k(sim::reactor::rod::val_t type) const;
 	virtual void display(std::ostream& o) const;
 
+	virtual const char* get_name() const { return "Control Rod"; }
+	virtual bool should_display() const { return true; }
+
 public:
 
 	control_rod(double limit);
diff --git a/src/reactor/coolant/pipe.cpp b/src/reactor/coolant/pipe.cpp
index 0e46ea5..49f5c55 100644
--- a/src/reactor/coolant/pipe.cpp
+++ b/src/reactor/coolant/pipe.cpp
@@ -3,11 +3,6 @@
 
 using namespace sim::reactor::coolant;
 
-const char* pipe::get_name() const
-{
-	return "Coolant Pipe";
-}
-
 double pipe::get_k(val_t type) const
 {
 	switch(type)
diff --git a/src/reactor/coolant/pipe.hpp b/src/reactor/coolant/pipe.hpp
index 6530366..13405a5 100644
--- a/src/reactor/coolant/pipe.hpp
+++ b/src/reactor/coolant/pipe.hpp
@@ -8,8 +8,10 @@ namespace sim::reactor::coolant
 
 class pipe : public sim::reactor::rod
 {
-	virtual const char* get_name() const;
 	virtual double get_k(sim::reactor::rod::val_t type) const;
+	
+	virtual const char* get_name() const { return "Coolant Pipe"; }
+	virtual bool should_display() const { return true; }
 
 public:
 
diff --git a/src/reactor/fuel/fuel_rod.cpp b/src/reactor/fuel/fuel_rod.cpp
index e366526..b476fc8 100644
--- a/src/reactor/fuel/fuel_rod.cpp
+++ b/src/reactor/fuel/fuel_rod.cpp
@@ -14,11 +14,6 @@ void fuel_rod::display(std::ostream& o) const
 	o << "Energy: " << s.get_energy() << "\n";
 }
 
-const char* fuel_rod::get_name() const
-{
-	return "Fuel";
-}
-
 double fuel_rod::get_k(val_t type) const
 {
 	switch(type)
diff --git a/src/reactor/fuel/fuel_rod.hpp b/src/reactor/fuel/fuel_rod.hpp
index f1b2677..5f1d5b3 100644
--- a/src/reactor/fuel/fuel_rod.hpp
+++ b/src/reactor/fuel/fuel_rod.hpp
@@ -11,10 +11,12 @@ class fuel_rod : public sim::reactor::rod
 {
 	sample s;
 	
-	virtual const char* get_name() const;
 	virtual double get_k(sim::reactor::rod::val_t type) const;
 	virtual void display(std::ostream& o) const;
 	
+	virtual const char* get_name() const { return "Fuel"; }
+	virtual bool should_display() const { return true; }
+	
 public:
 
 	fuel_rod(double fuel, double mass);
diff --git a/src/reactor/reactor.hpp b/src/reactor/reactor.hpp
index 52d585a..a5cafc0 100644
--- a/src/reactor/reactor.hpp
+++ b/src/reactor/reactor.hpp
@@ -30,20 +30,20 @@ struct reactor
 		// do interactions
 		for(int x = 1; x < W; x++)
 		{
-			rods[x][0]->interact(rods[x - 1][0]);
+			rods[x][0]->interact(rods[x - 1][0], secs);
 		}
 
 		for(int y = 1; y < H; y++)
 		{
-			rods[0][y]->interact(rods[0][y - 1]);
+			rods[0][y]->interact(rods[0][y - 1], secs);
 		}
 
 		for(int y = 1; y < H; y++)
 		for(int x = 1; x < W; x++)
 		{
 			rod* r = rods[x][y];
-			r->interact(rods[x - 1][y]);
-			r->interact(rods[x][y - 1]);
+			r->interact(rods[x - 1][y], secs);
+			r->interact(rods[x][y - 1], secs);
 		}
 
 		// do updates
diff --git a/src/reactor/rod.cpp b/src/reactor/rod.cpp
index a45bb7e..b8390f5 100644
--- a/src/reactor/rod.cpp
+++ b/src/reactor/rod.cpp
@@ -20,12 +20,12 @@ double rod::extract(val_t type, double k, double o)
 	return v;
 }
 
-void rod::interact(rod* o)
+void rod::interact(rod* o, double secs)
 {
 	for(int i = 0; i < rod::VAL_N; i++)
 	{
 		val_t v = (val_t)i;
-		add(v, o->extract(v, get_k(v), get(v)));
+		add(v, o->extract(v, secs * get_k(v), get(v)));
 	}
 }
 
@@ -39,8 +39,3 @@ void rod::update_rod()
 	}
 }
 
-void rod::display(std::ostream& o) const
-{
-
-}
-
diff --git a/src/reactor/rod.hpp b/src/reactor/rod.hpp
index d45152f..9da2df4 100644
--- a/src/reactor/rod.hpp
+++ b/src/reactor/rod.hpp
@@ -19,14 +19,16 @@ public:
 		N_FAST = 2
 	};
 
-	virtual void interact(rod* o);
-	virtual void update(double secs) = 0;
+	virtual void interact(rod* o, double secs);
+	virtual void update(double secs) { };
 	virtual void add(val_t type, double v);
 	virtual double extract(val_t type, double k, double o);
 	virtual double get(val_t type) const;
 
 	friend std::ostream& operator<<(std::ostream& o, const rod& r)
 	{
+		if(!r.should_display()) return o;
+
 		o << "Name: " << r.get_name() << "\n";
 		r.display(o);
 		o << "Heat: " << r.get(val_t::HEAT) << "\n";
@@ -41,9 +43,10 @@ protected:
 	double vals_in[VAL_N] = {0};
 	double vals[VAL_N] = {0};
 
-	virtual void display(std::ostream& o) const;
-	virtual double get_k(val_t type) const = 0;
-	virtual const char* get_name() const = 0;
+	virtual void display(std::ostream& o) const { };
+	virtual double get_k(val_t type) const { return 0; }
+	virtual const char* get_name() const { return "Empty"; }
+	virtual bool should_display() const { return false; }
 
 	void update_rod();
 };