Just hold the D shape and alternate the bass notes, doing a picking style like below.
e----------------------------------------------------------|
B----------------------------------------------------------|
G------2------2-----2-----2-------2-----2------2------2----|
D----0------0-----0-----0-------0-----0------0------0------|
A--4------4-----0-----0------------------------------------|
E----------------------------0------0------3------3--------|
e----------------------------------------------------------|
B--------3------3----3------3------3-----3------3------3---|
G------2------2-----2-----2-------2-----2------2------2----|
D----------------------------------------------------------|
A--4-------4------0-----0----------------------------------|
E----------------------------0--------0------3------3------|