diff --git a/qpms/cytmatrices.pxd b/qpms/cytmatrices.pxd
index c955257..51641d9 100644
--- a/qpms/cytmatrices.pxd
+++ b/qpms/cytmatrices.pxd
@@ -11,6 +11,8 @@ cdef class TMatrixInterpolator:
     cdef double *freqs_su
     cdef size_t nfreqs
     cdef qpms_tmatrix_interpolator_t *interp
+    cdef inline qpms_tmatrix_interpolator_t *rawpointer(self):
+        return self.interp
 
 cdef class CTMatrix: # N.B. there is another type called TMatrix in tmatrices.py!
     cdef readonly np.ndarray m # Numpy array holding the matrix data
@@ -23,3 +25,7 @@ cdef class CTMatrix: # N.B. there is another type called TMatrix in tmatrices.py
         Don't forget to reference the BaseSpec object itself when storing the pointer anywhere!!!
         '''
         return &(self.t)
+
+
+
+
diff --git a/qpms/cytmatrices.pyx b/qpms/cytmatrices.pyx
index fb19961..a15dc33 100644
--- a/qpms/cytmatrices.pyx
+++ b/qpms/cytmatrices.pyx
@@ -3,6 +3,7 @@ from .qpms_cdefs cimport *
 from .cybspec cimport BaseSpec
 from .cycommon import *
 from .cycommon cimport make_c_string
+from .cymaterials cimport EpsMuGenerator
 from .qpms_c cimport FinitePointGroup
 import warnings
 import os
@@ -114,3 +115,107 @@ cdef class CTMatrix: # N.B. there is another type called TMatrix in tmatrices.py
         tm = CTMatrix(spec, 0)
         tm.spherical_perm_fill(radius, freq, epsilon_int, epsilon_ext)
         return tm
+
+cdef class __MieParams:
+    # Not directly callable right now, serves just to be used by TMatrixGenerator.
+    cdef qpms_tmatrix_generator_sphere_param_t cparam
+    cdef EpsMuGenerator outside
+    cdef EpsMuGenerator inside
+    cdef inline  void *rawpointer(self):
+        return <void *>&(self.cparam)
+    
+    def __init__(self, outside, inside, r):
+        self.inside = inside
+        self.outside = outside
+        self.cparam.inside = self.inside.raw();
+        self.cparam.outside = self.outside.raw();
+        self.cparam.radius = r
+
+    property r:
+        def __get__(self):
+            return self.cparam.radius
+        def __set__(self, val):
+            self.cparam.radius = val
+
+cdef class __ArcCylinder:
+    cdef qpms_arc_cylinder_params_t p
+    cdef inline void *rawpointer(self):
+        return <void *> &(self.p)
+
+cdef class __ArcSphere:
+    cdef double r
+    cdef inline void *rawpointer(self):
+        return <void *> &(self.r)
+
+cdef qpms_arc_function_retval_t userarc(double theta, const void *params):
+    cdef object fun = <object> params
+    cdef qpms_arc_function_retval_t retval
+    retval.r, retval.beta = fun(theta)
+    return retval
+
+
+cdef class ArcFunction:
+    cdef qpms_arc_function_t g
+    cdef object holder
+    def __init__(self, what):
+        if isinstance(what, __ArcCylinder):
+            self.holder = what
+            self.g.function = qpms_arc_cylinder
+            self.g.params = (<__ArcCylinder?>self.holder).rawpointer()
+        elif isinstance(what, __ArcSphere):
+            self.holder = what
+            self.g.function = qpms_arc_sphere
+            self.g.params = (<__ArcSphere?>self.holder).rawpointer()
+        elif callable(what):
+            warnings.warn("Custom python (r, beta) arc functions are an experimental feature. Also expect it to be slow.")
+            self.holder = what
+            self.g.function = userarc
+            self.g.params = <const void *> self.holder
+        elif isinstance(what, ArcFunction): #Copy constructor
+            self.holder = what.holder
+            self.g = (<ArcFunction?>what).g
+            self.holder.rawpointer()
+
+cdef class __AxialSymParams:
+    cdef qpms_tmatrix_generator_axialsym_param_t p
+    cdef EpsMuGenerator outside
+    cdef EpsMuGenerator inside
+    cdef ArcFunction shape
+    cdef void * rawpointer(self):
+        return <void *> &(self.p)
+    property lMax_extend:
+        def __get__(self):
+            return self.p.lMax_extend
+        def __set__(self, val):
+            self.p.lMax_extend = val
+    def __init__(self, outside, inside, shape, *args, **kwargs):
+        self.outside = outside
+        self.p.outside = self.outside.g
+        self.inside = inside
+        self.p.inside = self.inside.g
+        self.shape = shape
+        self.p.shape = self.shape.g
+        if len(args)>0:
+            self.lMax_extend = args[0]
+        if 'lMax_extend' in kwargs.keys():
+            self.lMax_extend = kwargs['lMax_extend']
+
+cdef class TMatrixGenerator:
+    cdef qpms_tmatrix_generator_t g
+    cdef object holder
+    cdef qpms_tmatrix_generator_t raw(self):
+        return self.g
+    def __init__(self, what):
+        if isinstance(what, __MieParams):
+            self.holder = what
+            self.g.function = qpms_tmatrix_generator_sphere
+            self.g.params = (<__MieParams?>self.holder).rawpointer()
+        elif isinstance(what,__AxialSymParams):
+            self.holder = what
+            self.g.function = qpms_tmatrix_generator_axialsym
+            self.g.params = (<__AxialSymParams?>self.holder).rawpointer()
+        else:
+            raise ValueError("Can't construct TMatrixGenerator from that")
+
+
+
diff --git a/qpms/tmatrices.c b/qpms/tmatrices.c
index 6b27ad5..d1ce6ee 100644
--- a/qpms/tmatrices.c
+++ b/qpms/tmatrices.c
@@ -35,6 +35,7 @@
 
 #define SQ(x) ((x)*(x))
 #define MAX(x,y) ((x) < (y) ? (y) : (x))
+#define MIN(x,y) ((x) > (y) ? (y) : (x))
 
 qpms_tmatrix_t *qpms_tmatrix_init(const qpms_vswf_set_spec_t *bspec) {
   qpms_tmatrix_t *t = malloc(sizeof(qpms_tmatrix_t));
@@ -692,7 +693,7 @@ qpms_errno_t qpms_tmatrix_axialsym_fill(
 		qpms_tmatrix_t *t, complex double omega, qpms_epsmu_t outside,
 		qpms_epsmu_t inside,qpms_arc_function_t shape, qpms_l_t lMaxQR)
 {
-  QPMS_UNTESTED;
+  QPMS_UNTESTED; // TODO also check whether this is valid for all norms.
   const qpms_vswf_set_spec_t *bspec = t->spec;
   struct tmatrix_axialsym_integral_param_t p;
   p.k = qpms_wavenumber(omega, outside);
@@ -797,3 +798,16 @@ qpms_errno_t qpms_tmatrix_generator_axialsym(qpms_tmatrix_t *t, complex double o
       p->shape,
       p->lMax_extend);
 }
+
+qpms_errno_t qpms_tmatrix_generator_constant(qpms_tmatrix_t *t,
+    complex double omega, const void *tmorig) {
+  QPMS_UNTESTED;
+  // TODO more thorough check on bspec!
+  const qpms_tmatrix_t *orig = tmorig;
+  const size_t tocopy = SQ(MIN(t->spec->n, orig->spec->n));
+  memcpy(t->m, orig->m, tocopy*sizeof(complex double));
+  memset(t->m+tocopy, 0, (SQ(t->spec->n)-tocopy)*sizeof(complex double));
+  return QPMS_SUCCESS;
+}
+
+
diff --git a/qpms/tmatrices.h b/qpms/tmatrices.h
index ab21a56..a642011 100644
--- a/qpms/tmatrices.h
+++ b/qpms/tmatrices.h
@@ -241,6 +241,7 @@ complex double *qpms_apply_tmatrix(
  * qpms_tmatrix_generator_axialsym()
  * qpms_tmatrix_generator_interpolator()
  * qpms_tmatrix_generator_sphere()
+ * qpms_tmatrix_generator_constant()
  */
 typedef struct qpms_tmatrix_generator_t {
 	qpms_errno_t (*function) (qpms_tmatrix_t *t, ///< T-matrix to fill.
@@ -250,6 +251,16 @@ typedef struct qpms_tmatrix_generator_t {
 	const void *params; ///< Parameter pointer passed to the function.
 } qpms_tmatrix_generator_t;
 
+/// Implementation of qpms_matrix_generator_t that just copies a constant matrix.
+/** N.B. this does almost no checks at all, so use it only for t-matrices with
+ * the same base spec.
+ */
+qpms_errno_t qpms_tmatrix_generator_constant(qpms_tmatrix_t *t,
+		complex double omega,
+		/// Source T-matrix, real type is (const qpms_tmatrix_t*).
+		const void *tmatrix_orig
+		);
+
 /* Fuck this, include the whole <gsl/gsl_spline.h>
 typedef struct gsl_spline gsl_spline; // Forward declaration for the interpolator struct
 typedef struct gsl_interp_type gsl_interp_type;