diff --git a/NAMESPACE b/NAMESPACE
index 1a5b79cd..38fb75ea 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -83,6 +83,7 @@ S3method(set_observed_data,epiworld_lfmcmc)
 S3method(set_par_names,epiworld_lfmcmc)
 S3method(set_param,epiworld_model)
 S3method(set_proposal_fun,epiworld_lfmcmc)
+S3method(set_rand_engine_lfmcmc,epiworld_lfmcmc)
 S3method(set_simulation_fun,epiworld_lfmcmc)
 S3method(set_stats_names,epiworld_lfmcmc)
 S3method(set_summary_fun,epiworld_lfmcmc)
@@ -209,6 +210,7 @@ export(set_prob_recovery)
 export(set_prob_recovery_fun)
 export(set_prob_recovery_ptr)
 export(set_proposal_fun)
+export(set_rand_engine_lfmcmc)
 export(set_recovery_enhancer)
 export(set_recovery_enhancer_fun)
 export(set_recovery_enhancer_ptr)
diff --git a/R/LFMCMC.R b/R/LFMCMC.R
index 4b31de96..bba116f1 100644
--- a/R/LFMCMC.R
+++ b/R/LFMCMC.R
@@ -4,14 +4,18 @@
 #' @aliases epiworld_lfmcmc
 #' @details
 #' TODO: Detail LFMCMC
+#' TODO: Add params
 #' @returns
 #' - The `LFMCMC`function returns a model of class [epiworld_lfmcmc].
 #' @examples
 #' model_lfmcmc <- LFMCMC()
 #' @export
-LFMCMC <- function() {
+LFMCMC <- function(model) {
+  if (!inherits(model, "epiworld_model"))
+    stop("model should be of class 'epiworld_model'. It is of class ", class(model))
+
   structure(
-    LFMCMC_cpp(),
+    LFMCMC_cpp(model),
     class = c("epiworld_lfmcmc")
   )
 }
@@ -96,6 +100,19 @@ set_kernel_fun.epiworld_lfmcmc <- function(lfmcmc, fun) {
   invisible(lfmcmc)
 }
 
+#' @rdname LFMCMC
+#' @param lfmcmc LFMCMC model
+#' @param eng The rand engine
+#' @returns The lfmcmc model with the engine set
+#' @export
+set_rand_engine_lfmcmc <- function(lfmcmc, eng) UseMethod("set_rand_engine_lfmcmc")
+
+#' @export
+set_rand_engine_lfmcmc.epiworld_lfmcmc <- function(lfmcmc, eng) {
+  set_rand_engine_lfmcmc_cpp(lfmcmc, eng)
+  invisible(lfmcmc)
+}
+
 #' @rdname LFMCMC
 #' @param lfmcmc LFMCMC model
 #' @param s The rand engine seed
diff --git a/R/cpp11.R b/R/cpp11.R
index 1106bbfd..110cb1cd 100644
--- a/R/cpp11.R
+++ b/R/cpp11.R
@@ -220,8 +220,8 @@ ModelSEIRMixing_cpp <- function(name, n, prevalence, contact_rate, transmission_
   .Call(`_epiworldR_ModelSEIRMixing_cpp`, name, n, prevalence, contact_rate, transmission_rate, incubation_days, recovery_rate, contact_matrix)
 }
 
-LFMCMC_cpp <- function() {
-  .Call(`_epiworldR_LFMCMC_cpp`)
+LFMCMC_cpp <- function(m) {
+  .Call(`_epiworldR_LFMCMC_cpp`, m)
 }
 
 run_lfmcmc_cpp <- function(lfmcmc, params_init_, n_samples_, epsilon_) {
@@ -264,6 +264,10 @@ set_kernel_fun_cpp <- function(lfmcmc, fun) {
   .Call(`_epiworldR_set_kernel_fun_cpp`, lfmcmc, fun)
 }
 
+set_rand_engine_lfmcmc_cpp <- function(lfmcmc, eng) {
+  .Call(`_epiworldR_set_rand_engine_lfmcmc_cpp`, lfmcmc, eng)
+}
+
 seed_lfmcmc_cpp <- function(lfmcmc, s) {
   .Call(`_epiworldR_seed_lfmcmc_cpp`, lfmcmc, s)
 }
diff --git a/man/LFMCMC.Rd b/man/LFMCMC.Rd
index 32f63a34..f15c0f50 100644
--- a/man/LFMCMC.Rd
+++ b/man/LFMCMC.Rd
@@ -9,13 +9,14 @@
 \alias{set_simulation_fun}
 \alias{set_summary_fun}
 \alias{set_kernel_fun}
+\alias{set_rand_engine_lfmcmc}
 \alias{seed_lfmcmc}
 \alias{set_par_names}
 \alias{set_stats_names}
 \alias{print.epiworld_lfmcmc}
 \title{Likelihood-Free Markhov Chain Monte Carlo (LFMCMC)}
 \usage{
-LFMCMC()
+LFMCMC(model)
 
 run_lfmcmc(lfmcmc, params_init_, n_samples_, epsilon_)
 
@@ -29,6 +30,8 @@ set_summary_fun(lfmcmc, fun)
 
 set_kernel_fun(lfmcmc, fun)
 
+set_rand_engine_lfmcmc(lfmcmc, eng)
+
 seed_lfmcmc(lfmcmc, s)
 
 set_par_names(lfmcmc, names)
@@ -50,6 +53,8 @@ set_stats_names(lfmcmc, names)
 
 \item{fun}{The LFMCMC kernel function}
 
+\item{eng}{The rand engine}
+
 \item{s}{The rand engine seed}
 
 \item{names}{The model stats names}
@@ -75,6 +80,8 @@ The lfmcmc model with the summary function added
 
 The lfmcmc model with the kernel function added
 
+The lfmcmc model with the engine set
+
 The lfmcmc model with the seed set
 
 The lfmcmc model with the parameter names added
@@ -88,6 +95,7 @@ Likelihood-Free Markhov Chain Monte Carlo (LFMCMC)
 }
 \details{
 TODO: Detail LFMCMC
+TODO: Add params
 }
 \examples{
 model_lfmcmc <- LFMCMC()
diff --git a/src/cpp11.cpp b/src/cpp11.cpp
index 39237a59..f4dd141f 100644
--- a/src/cpp11.cpp
+++ b/src/cpp11.cpp
@@ -391,10 +391,10 @@ extern "C" SEXP _epiworldR_ModelSEIRMixing_cpp(SEXP name, SEXP n, SEXP prevalenc
   END_CPP11
 }
 // lfmcmc.cpp
-SEXP LFMCMC_cpp();
-extern "C" SEXP _epiworldR_LFMCMC_cpp() {
+SEXP LFMCMC_cpp(SEXP m);
+extern "C" SEXP _epiworldR_LFMCMC_cpp(SEXP m) {
   BEGIN_CPP11
-    return cpp11::as_sexp(LFMCMC_cpp());
+    return cpp11::as_sexp(LFMCMC_cpp(cpp11::as_cpp<cpp11::decay_t<SEXP>>(m)));
   END_CPP11
 }
 // lfmcmc.cpp
@@ -468,6 +468,13 @@ extern "C" SEXP _epiworldR_set_kernel_fun_cpp(SEXP lfmcmc, SEXP fun) {
   END_CPP11
 }
 // lfmcmc.cpp
+SEXP set_rand_engine_lfmcmc_cpp(SEXP lfmcmc, SEXP eng);
+extern "C" SEXP _epiworldR_set_rand_engine_lfmcmc_cpp(SEXP lfmcmc, SEXP eng) {
+  BEGIN_CPP11
+    return cpp11::as_sexp(set_rand_engine_lfmcmc_cpp(cpp11::as_cpp<cpp11::decay_t<SEXP>>(lfmcmc), cpp11::as_cpp<cpp11::decay_t<SEXP>>(eng)));
+  END_CPP11
+}
+// lfmcmc.cpp
 SEXP seed_lfmcmc_cpp(SEXP lfmcmc, unsigned long long int s);
 extern "C" SEXP _epiworldR_seed_lfmcmc_cpp(SEXP lfmcmc, SEXP s) {
   BEGIN_CPP11
@@ -1016,7 +1023,7 @@ extern "C" SEXP _epiworldR_distribute_virus_to_set_cpp(SEXP agents_ids) {
 
 extern "C" {
 static const R_CallMethodDef CallEntries[] = {
-    {"_epiworldR_LFMCMC_cpp",                           (DL_FUNC) &_epiworldR_LFMCMC_cpp,                            0},
+    {"_epiworldR_LFMCMC_cpp",                           (DL_FUNC) &_epiworldR_LFMCMC_cpp,                            1},
     {"_epiworldR_ModelDiffNet_cpp",                     (DL_FUNC) &_epiworldR_ModelDiffNet_cpp,                      8},
     {"_epiworldR_ModelSEIRCONN_cpp",                    (DL_FUNC) &_epiworldR_ModelSEIRCONN_cpp,                     7},
     {"_epiworldR_ModelSEIRDCONN_cpp",                   (DL_FUNC) &_epiworldR_ModelSEIRDCONN_cpp,                    8},
@@ -1140,6 +1147,7 @@ static const R_CallMethodDef CallEntries[] = {
     {"_epiworldR_set_prob_recovery_fun_cpp",            (DL_FUNC) &_epiworldR_set_prob_recovery_fun_cpp,             3},
     {"_epiworldR_set_prob_recovery_ptr_cpp",            (DL_FUNC) &_epiworldR_set_prob_recovery_ptr_cpp,             3},
     {"_epiworldR_set_proposal_fun_cpp",                 (DL_FUNC) &_epiworldR_set_proposal_fun_cpp,                  2},
+    {"_epiworldR_set_rand_engine_lfmcmc_cpp",           (DL_FUNC) &_epiworldR_set_rand_engine_lfmcmc_cpp,            2},
     {"_epiworldR_set_recovery_enhancer_cpp",            (DL_FUNC) &_epiworldR_set_recovery_enhancer_cpp,             2},
     {"_epiworldR_set_recovery_enhancer_fun_cpp",        (DL_FUNC) &_epiworldR_set_recovery_enhancer_fun_cpp,         3},
     {"_epiworldR_set_recovery_enhancer_ptr_cpp",        (DL_FUNC) &_epiworldR_set_recovery_enhancer_ptr_cpp,         3},
diff --git a/src/lfmcmc.cpp b/src/lfmcmc.cpp
index 8866ccc4..44c466bd 100644
--- a/src/lfmcmc.cpp
+++ b/src/lfmcmc.cpp
@@ -15,11 +15,15 @@ using namespace epiworld;
 // https://github.com/UofUEpiBio/epiworld/tree/master/include/epiworld/math/lfmcmc
 
 [[cpp11::register]]
-SEXP LFMCMC_cpp() {
+SEXP LFMCMC_cpp(
+    SEXP m
+) {
     WrapLFMCMC(lfmcmc_ptr)(
         new LFMCMC<TData_default>()
     );
 
+    lfmcmc_ptr->set_rand_engine(cpp11::external_pointer<Model<>>(m)->get_rand_endgine());
+
     return lfmcmc_ptr;
 }
 
@@ -131,7 +135,6 @@ SEXP set_summary_fun_cpp(
 }
 
 // LFMCMC Kernel Function
-// TODO: clean up these really long lines
 [[cpp11::register]]
 SEXP create_LFMCMCKernelFun_cpp(
     cpp11::function fun
@@ -159,6 +162,18 @@ SEXP set_kernel_fun_cpp(
     return lfmcmc;
 }
 
+// Rand Engine
+[[cpp11::register]]
+SEXP set_rand_engine_lfmcmc_cpp(
+    SEXP lfmcmc,
+    SEXP eng
+) {
+    cpp11::external_pointer<std::mt19937> eng_ptr(eng);
+    WrapLFMCMC(lfmcmc_ptr)(lfmcmc);
+    lfmcmc_ptr->set_rand_engine(*eng_ptr);
+    return lfmcmc;
+}
+
 // s should be of type epiworld_fast_uint
 [[cpp11::register]]
 SEXP seed_lfmcmc_cpp(
diff --git a/vignettes/likelihood-free-mcmc.Rmd b/vignettes/likelihood-free-mcmc.Rmd
index 9acba8bc..d90f1bb5 100644
--- a/vignettes/likelihood-free-mcmc.Rmd
+++ b/vignettes/likelihood-free-mcmc.Rmd
@@ -56,7 +56,7 @@ print(model_sir)
 
 ## Extract Observed data
 ```{r extract-obs-data}
-obs_data <- get_today_total(model_sir)
+obs_data <- as.integer(get_today_total(model_sir))
 ```
 
 ## Setup LFMCMC
@@ -100,18 +100,17 @@ par0 <- c(.5, .5)
 ## Run LFMCMC
 ```{r lfmcmc-run}
 # TODO: make these work
-lfmcmc_model <- LFMCMC() |>
+lfmcmc_model <- LFMCMC(model_sir) |>
   set_simulation_fun(simfun) |>
   set_summary_fun(sumfun) |>
   set_proposal_fun(propfun) |>
-  set_kernel_fun(kernfun)
-#   set_observed_data(obs_dat) |>
-#   run_lfmcmc(par0, 2000, 1)
+  set_kernel_fun(kernfun) |>
+  set_observed_data(obs_data)
+# run_lfmcmc(par0, 2000, 1)
 
 # lfmcmc_model
 
-# lfmcmc_model <- seed(lfmcmc_model, model_seed) |>
-#   set_par_names(c("Immune recovery", "Infectiousness")) |>
+# lfmcmc_model <- set_par_names(c("Immune recovery", "Infectiousness")) |>
 #   set_stats_names(get_states(model_sir)) |>
 #   print()
 ```