diff --git a/src/SimNDT/gui/constants.py b/src/SimNDT/gui/constants.py
new file mode 100644
index 0000000..69ad958
--- /dev/null
+++ b/src/SimNDT/gui/constants.py
@@ -0,0 +1,61 @@
+__author__ = 'Miguel Molero'
+
+import sys
+import os 
+
+FONT_NAME = "Helvetica"
+SCALE_UI = 1
+
+if sys.platform == "darwin":
+	FONT_SIZE_1 = 13
+	FONT_SIZE_2 = 12
+	FONT_SIZE_3 = 11
+else:
+	FONT_SIZE_1 = 10
+	FONT_SIZE_2 = 9
+	FONT_SIZE_3 = 8
+
+if os.environ.get('HIGH_DPI') == "1":
+	FONT_SIZE_1 = 13
+	FONT_SIZE_2 = 12
+	FONT_SIZE_3 = 11
+	SCALE_UI    = 1.4
+
+
+
+if (sys.version_info > (3, 0)):
+
+	RHO = chr(961)
+	MU  = chr(956)
+	LAMBDA = chr(955)
+	RHO_LABEL = chr(961) + " (kg/m<sup>3</sup>)"
+	LAMBDA_LABEL = chr(955) + " (GPa)"
+	MU_LABEL = chr(956) + " (GPa)"
+	ETAV_LABEL = chr(951) + "<sub>"+chr(955)+"</sub>" + " (GPa)"
+	ETAS_LABEL = chr(951) + "<sub>"+chr(956)+"</sub>" + " (GPa)"
+
+	VL_LABEL = " V<sub>L</sub> " + " (m/s)"
+	VT_LABEL = " V<sub>T</sub> " + " (m/s)"
+
+	MARK = u"\u2713"
+	CROSS = u"\u2718"
+
+else:
+
+	RHO =  u"\u03C1"
+	MU = u"\u03BC"
+	LAMBDA = u"\u03BB"
+	RHO_LABEL = u"\u03C1" + " (kg/m<sup>3</sup>)"
+	LAMBDA_LABEL = u"\u03BB" + " (GPa)"
+	MU_LABEL = u"\u03BC" + " (GPa)"
+	ETAV_LABEL = u'\u0397' + "<sub>" + u'\u03BB' + "</sub>" + " (GPa)"
+	ETAS_LABEL = u'\u0397' + "<sub>" + u'\u03BC' + "</sub>" + " (GPa)"
+
+	VL_LABEL = " V<sub>L</sub> " + " (m/s)"
+	VT_LABEL = " V<sub>T</sub> " + " (m/s)"
+
+	MARK = u"\u2713"
+	CROSS = u"\u2718"
+
+
+DEGREE_ANGLE = chr(176)