diff --git a/petri/src/lib.rs b/petri/src/lib.rs
index 37b1615..66521e1 100644
--- a/petri/src/lib.rs
+++ b/petri/src/lib.rs
@@ -20,9 +20,19 @@ pub struct Chunk {
 pub struct Rule {
 	pub from: RulePattern,
 	pub to: RulePattern,
-	// probability
-	// flip
-	// rotate
+	// enabled: bool
+	// probability: u8
+	// flip:
+	// rotate:
+}
+
+impl Rule {
+	pub fn new() -> Self {
+		Self {
+			from: RulePattern::new(),
+			to: RulePattern::new(),
+		}
+	}
 }
 
 impl Chunk {
@@ -106,8 +116,6 @@ impl Dish {
 		let x = random::<usize>() % CHUNK_SIZE;
 		let y = random::<usize>() % CHUNK_SIZE;
 		let rule = random::<usize>() % self.rules.len();
-		// let rule = &self.rules[rule];
-
 		self.fire_rule(rule, x, y);
 	}
 
@@ -164,6 +172,14 @@ pub struct RulePattern {
 }
 
 impl RulePattern {
+	pub fn new() -> Self {
+		Self {
+			width: 1,
+			height: 1,
+			contents: vec![None],
+		}
+	}
+
 	pub fn get(&self, x: usize, y: usize) -> Option<Cell> {
 		if x >= self.width || y >= self.height {
 			None
@@ -193,6 +209,44 @@ impl RulePattern {
 	pub fn width(&self) -> usize {
 		self.width
 	}
+
+	pub fn extend_left(&mut self) {
+		let new_width = self.width + 1;
+		let mut new_vec = vec![None; new_width * self.height];
+		for y in 0..self.height {
+			for x in 0..self.width {
+				new_vec[x + new_width * y + 1] = self.contents[x + self.width * y];
+			}
+		}
+		self.width += 1;
+		self.contents = new_vec;
+	}
+
+	pub fn extend_right(&mut self) {
+		let new_width = self.width + 1;
+		let mut new_vec = vec![None; new_width * self.height];
+		for y in 0..self.height {
+			for x in 0..self.width {
+				new_vec[x + new_width * y] = self.contents[x + self.width * y];
+			}
+		}
+		self.width += 1;
+		self.contents = new_vec;
+	}
+
+	pub fn extend_up(&mut self) {
+		for _ in 0..self.width {
+			self.contents.insert(0, None);
+		}
+		self.height += 1;
+	}
+
+	pub fn extend_down(&mut self) {
+		for _ in 0..self.width {
+			self.contents.push(None);
+		}
+		self.height += 1;
+	}
 }
 
 impl Cell {
diff --git a/uscope/src/main.rs b/uscope/src/main.rs
index d1acfd3..7c26fb9 100644
--- a/uscope/src/main.rs
+++ b/uscope/src/main.rs
@@ -63,6 +63,9 @@ impl eframe::App for UScope {
 			for rule in &mut self.dish.rules {
 				rule_editor(ui, rule, &self.celltypes);
 			}
+			if ui.button("add rule").clicked() {
+				self.dish.rules.push(Rule::new());
+			}
 		});
 		CentralPanel::default().show(ctx, |ui| {
 			let bounds = ui.available_rect_before_wrap();
@@ -97,20 +100,74 @@ fn paint_chunk(painter: Painter, chunk: &Chunk, cells: &[CellData]) {
 const CSIZE: f32 = 24.;
 const OUTLINE: (f32, Color32) = (1., Color32::GRAY);
 fn rule_editor(ui: &mut Ui, rule: &mut Rule, cells: &[CellData]) {
-	let patt_height = rule.from.height();
-	let patt_width = rule.from.height();
+	let cells_y = rule.from.height();
+	let cells_x = rule.from.width();
+	let margin = 8.;
+	let patt_width = CSIZE * cells_x as f32;
+	let patt_height = CSIZE * cells_y as f32;
 
 	let (_, bounds) = ui.allocate_space(Vec2::new(
-		CSIZE * (patt_width * 2 + 1) as f32,
-		CSIZE * patt_height as f32,
+		patt_width * 2. + margin * 4. + CSIZE,
+		patt_height + margin * 2.,
 	));
-	for x in 0..patt_width {
-		for y in 0..patt_height {
-			rule_cell_edit(ui, bounds.min, &mut rule.from, x, y, cells);
-			let offset = Vec2::X * (patt_width as f32 + 1.) * CSIZE;
-			rule_cell_edit(ui, bounds.min + offset, &mut rule.to, x, y, cells);
+
+	let from_cells_rect = Rect::from_min_size(
+		bounds.min + Vec2::splat(margin),
+		Vec2::new(patt_width, patt_height),
+	);
+	let to_cells_rect = Rect::from_min_size(
+		bounds.min + Vec2::splat(margin) + Vec2::X * (patt_width + margin * 2. + CSIZE),
+		Vec2::new(patt_width, patt_height),
+	);
+
+	for x in 0..cells_x {
+		for y in 0..cells_y {
+			rule_cell_edit(ui, from_cells_rect.min, &mut rule.from, x, y, cells);
+			rule_cell_edit(ui, to_cells_rect.min, &mut rule.to, x, y, cells);
 		}
 	}
+	let mut resize_box = |x, y, w, h| {
+		let rect_a = Rect::from_min_size(Pos2::new(x, y), Vec2::new(w, h));
+		let a = ui.allocate_rect(rect_a, Sense::click());
+		let rect_b = rect_a.translate(to_cells_rect.min - from_cells_rect.min);
+		let b = ui.allocate_rect(rect_b, Sense::click());
+		let result = a.union(b);
+		let color = if result.hovered() {
+			Color32::GRAY
+		} else {
+			Color32::DARK_GRAY
+		};
+		ui.painter_at(bounds).rect_filled(rect_a, 0., color);
+		ui.painter_at(bounds).rect_filled(rect_b, 0., color);
+
+		result.clicked()
+	};
+	if resize_box(bounds.min.x, bounds.min.y + margin, margin, patt_height) {
+		rule.from.extend_left();
+		rule.to.extend_left();
+	}
+	if resize_box(
+		from_cells_rect.max.x,
+		bounds.min.y + margin,
+		margin,
+		patt_height,
+	) {
+		rule.from.extend_right();
+		rule.to.extend_right();
+	}
+	if resize_box(bounds.min.x + margin, bounds.min.y, patt_width, margin) {
+		rule.from.extend_up();
+		rule.to.extend_up();
+	}
+	if resize_box(
+		bounds.min.x + margin,
+		bounds.max.y - margin,
+		patt_width,
+		margin,
+	) {
+		rule.from.extend_down();
+		rule.to.extend_down();
+	}
 }
 
 fn rule_cell_edit(