diff --git a/pangeo_forge_recipes/builders/__init__.py b/pangeo_forge_recipes/builders/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/pangeo_forge_recipes/builders/cmip.py b/pangeo_forge_recipes/builders/cmip.py
new file mode 100644
index 00000000..cca707b5
--- /dev/null
+++ b/pangeo_forge_recipes/builders/cmip.py
@@ -0,0 +1,67 @@
+from typing import List, Optional, Union
+
+from cmip6_preprocessing.postprocessing import match_metrics
+from cmip6_preprocessing.preprocessing import combined_preprocessing
+from cmip6_preprocessing.utils import google_cmip_col
+
+from ..patterns import pattern_from_file_sequence
+from ..recipes import XarrayZarrRecipe
+
+
+def cmip6_weighted_mean_recipe(
+    facets: dict,
+    weight_coord: str,
+    mean_dims: Union[List[str], str],
+    coarsen_time: Optional[int] = None,
+) -> XarrayZarrRecipe:
+
+    # Initialize CMIP6 catalog
+    col = google_cmip_col()
+
+    # Get path to variable data according to facets
+    # Note: might be superceded by opener refactor (custom opener which takes facets as kwargs)
+    cat = col.search(**facets)
+    path_list = cat.df["zstore"].tolist()
+    assert len(path_list) == 1
+    path = path_list[0]
+
+    # Load all available weights to enable imperfect matching, see:
+    # https://cmip6-preprocessing.readthedocs.io/en/latest/postprocessing.html#Handling-grid-metrics-in-CMIP6
+    cat_weight = col.search(
+        variable_id=weight_coord, source_id=facets["source_id"], grid_label=facets["grid_label"],
+    )
+    ddict_weight = cat_weight.to_dataset_dict(
+        zarr_kwargs={"consolidated": True, "use_cftime": True},
+        preprocess=combined_preprocessing,
+        aggregate=False,
+    )
+
+    def process_input(ds, fname):
+        ds = combined_preprocessing(ds)
+
+        ddict = dict(blank=ds)
+        ddict = match_metrics(ddict, ddict_weight, [weight_coord])
+
+        assert len(ddict) == 1
+        _, ds_out = ddict.popitem()
+
+        # TODO: write weight provenance to ds_out attributes here
+        ds_out = ds_out.weighted(ds_out[weight_coord].fillna(0)).mean(mean_dims)
+
+        if coarsen_time is not None:
+            ds_out = ds_out.coarsen(time=coarsen_time, boundary="trim").mean()
+
+        return ds_out
+
+    bypass_open = True
+    pattern = pattern_from_file_sequence(
+        [path], "time", is_opendap=bypass_open,  # Haha, okay this is weird, obviously.
+    )
+    xarray_open_kwargs = dict(engine="zarr")
+    recipe = XarrayZarrRecipe(
+        pattern,
+        target_chunks={"time": 1},
+        xarray_open_kwargs=xarray_open_kwargs,
+        process_input=process_input,
+    )
+    return recipe
diff --git a/pangeo_forge_recipes/patterns.py b/pangeo_forge_recipes/patterns.py
index 36460919..a1e967de 100644
--- a/pangeo_forge_recipes/patterns.py
+++ b/pangeo_forge_recipes/patterns.py
@@ -151,11 +151,11 @@ def __init__(
         self.fsspec_open_kwargs = fsspec_open_kwargs if fsspec_open_kwargs else {}
         self.query_string_secrets = query_string_secrets if query_string_secrets else {}
         self.is_opendap = is_opendap
-        if self.fsspec_open_kwargs and self.is_opendap:
-            raise ValueError(
-                "OPeNDAP inputs are not opened with `fsspec`. "
-                "`is_opendap` must be `False` when passing `fsspec_open_kwargs`."
-            )
+        # if self.fsspec_open_kwargs and self.is_opendap:
+        #    raise ValueError(
+        #        "OPeNDAP inputs are not opened with `fsspec`. "
+        #        "`is_opendap` must be `False` when passing `fsspec_open_kwargs`."
+        #    )
 
     def __repr__(self):
         return f"<FilePattern {self.dims}>"
diff --git a/pangeo_forge_recipes/recipes/xarray_zarr.py b/pangeo_forge_recipes/recipes/xarray_zarr.py
index 23ce9c1a..e286bb16 100644
--- a/pangeo_forge_recipes/recipes/xarray_zarr.py
+++ b/pangeo_forge_recipes/recipes/xarray_zarr.py
@@ -716,15 +716,15 @@ def __post_init__(self):
                 self.cache_inputs = False
             if self.open_input_with_fsspec_reference:
                 raise ValueError("Can't generate references on opendap inputs")
-            if "engine" in self.xarray_open_kwargs:
-                if self.xarray_open_kwargs["engine"] != "netcdf4":
-                    raise ValueError(
-                        "Opendap inputs only work with `xarray_open_kwargs['engine'] == 'netcdf4'`"
-                    )
-            else:
-                new_kw = self.xarray_open_kwargs.copy()
-                new_kw["engine"] = "netcdf4"
-                self.xarray_open_kwargs = new_kw
+            # if "engine" in self.xarray_open_kwargs:
+            # if self.xarray_open_kwargs["engine"] != "netcdf4":
+            #    raise ValueError(
+            #        "Opendap inputs only work with `xarray_open_kwargs['engine'] == 'netcdf4'`"
+            #    )
+            # else:
+            #    new_kw = self.xarray_open_kwargs.copy()
+            #    new_kw["engine"] = "netcdf4"
+            #    self.xarray_open_kwargs = new_kw
         elif self.cache_inputs is None:
             self.cache_inputs = True  # old defult
 
diff --git a/setup.cfg b/setup.cfg
index d4a8d695..deafc820 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -60,7 +60,7 @@ max-line-length = 100
 
 [isort]
 known_first_party=pangeo_forge_recipes
-known_third_party=aiohttp,apache_beam,click,dask,fsspec,fsspec_reference_maker,mypy_extensions,numpy,pandas,prefect,pytest,pytest_lazyfixture,setuptools,xarray,yaml,zarr
+known_third_party=aiohttp,apache_beam,click,cmip6_preprocessing,dask,fsspec,fsspec_reference_maker,mypy_extensions,numpy,pandas,prefect,pytest,pytest_lazyfixture,setuptools,xarray,yaml,zarr
 multi_line_output=3
 include_trailing_comma=True
 force_grid_wrap=0