I would like to multiply tensors R = {R_1, R_2, ..., R_M} and X = {X_1, X_2, ..., X_M} where R_i and X_i are 3×3 and 3×N_i matrices, respectively. How can I make maximum use of NumPy functionalities during the formation of the R_i × X_i arrays?

My MWE is the following:

import numpy as np

np.random.seed(0)

M = 5
R = [np.random.rand(3, 3) for _ in range(M)]
X = []
for i in range(M):
    N_i = np.random.randint(1, 6)
    X_i = np.random.rand(3, N_i)
    X.append(X_i)
    
result = np.zeros((3, 0))
for i in range(M):
    R_i = R[i]
    X_i = X[i]
    result = np.hstack((result, np.dot(R_i, X_i)))

print(result)